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Last update 4 October 1999
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Effect of oxygen availability on nitrogen fixation by two Lotus species under flooded conditions. James, E.K. ; Crawford, R.M.M. Journal of experimental botany. 1998. 49:599-609.
The pasture legumes Lotus uliginosus (Schk.) and Lotus corniculatus (L.), known to differ in their tolerance to flooding, were inoculated with Rhizobium loti and flooded for 60 d while subjected to two levels of dissolved pO2: 0.241 and 0.094 micromoles ml-(-1). L. uliginosus showed significantly greater growth (shoot and root) and N2 fixation under both pO2s, compared to L. corniculatus, although growth and N2 fixation by L. corniculatus was not affected by the low pO2. Surprisingly, in L. uliginosus., growth, nodulation and N2 fixation were all increased by low pO2 while nodulation of L. corniculatus was unaffected by low pO2. The highest rates of endogenous ethylene production were found with L. corniculatus where low pO2 plants showed a significant increase over that of the higher pO2 plants while L. uliginosus plants showed a decline. Root porosity of L. uliginosus doubled in the low pO2-treatment from a mean of 14.5% in high pO2 roots to 28.5%, whereas that of L. corniculatus was relatively unaffected by pO2, being 7% and 9% for high and low pO2 plants, respectively. The structure of nodules differed little between species and treatments, although nodules/nodulated roots from the L. uliginosus plants had particularly profuse lenticels and aerenchyma. However, L. corniculatus nodules, especially those grown in the lower pO2 showed signs of early senescence with vacuolation of infected cells and green coloration when cut open. Leghaemoglobin (Lb) concentrations in nodules from both species were unaffected by low pO2, although that of L. corniculatus nodules, regardless of pO2, was significantly greater than L. uliginosus. Concentrations of the intercellular glycoprotein recognized by the monoclonal antibody MAC265 were significantly reduced in nodules from the low pO2 treatment in both species. Immunogold labelling showed that the MAC265 antigen was localized primarily within intercellular spaces within nodule cortices from both Lotus species. A marked decrease in deposition of the MAC265 antigen within the cortices of L. uliginosus nodules grown in the lower pO2. is discussed in terms of the relative abilities of the two Lotus spp. to maintain an O2 supply to the N2-fixing bacteroids within submerged nodules.
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Genetic manipulation of condensed tannins in higher plants. II. Analysis of birdsfoot trefoil plants harboring antisense dihydroflavonol reductase constructs. Robbins, M. P.; Bavage, A. D.; Strudwicke, C.; Morris, P. 1998. Plant Physiology. 116:1133-1144.
Transgenic birdsfoot trefoil (Lotus corniculatus) plants harbouring antisense dihydroflavonol reductase (dihydrokaempferol 4-reductase) (AS-DFR) sequences were produced and analysed. In initial experiments the effect of introducing three different antisense Antirrhinum majus DFR constructs into a single recipient genotype (S50) was assessed. There were no obvious effects on plant biomass, but levels of condensed tannins showed a statistical reduction in leaf, stem and root tissues of some of the antisense lines. Transformation events were also found, which resulted in increased levels of condensed tannins. In subsequent experiments a detailed study of AS-DFR phenotypes was carried out in genotype S33 using pMAJ2 (an antisense construct comprising the 5' half of the A. majus cDNA). In this case, reduced tannin levels were found in leaf and stem tissues and in juvenile shoot tissues. Analysis of soluble flavonoids and isoflavonoids in tannin down-regulated shoot tissues indicated few obvious default products. When two S33 AS-DFR lines were outcrossed, there was an underrepresentation of transgene sequences in progeny plants and no examples of inheritance of an antisense phenotype were observed. This is the first report of the genetic manipulation of condensed tannin biosynthesis in higher plants.
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Notes on the biology and phenology of Zygaena (Zygaena) filipendulae (Linnaeus, 1758) and Z. (Z.) trifolii (Esper, 1783) (Lepidoptera: Zygaenidae) in Cornwall. Tremewan, W. G. Entomologist's Gazette. 1998. V 49:91-97.
Details of observations made in 1997 of Z. filipendulae, Z. trifolii and Z. trifolii decreta in Cornwall (at Boskednan, near Redruth, St. Agnes Head, Constantine Bay, St. Michael's Mount, Church Cove, and Porkellis), UK, are listed. The larvae of all 3 species were observed feeding on Lotus corniculatus and L. uliginosus. The emergence dates and food plants are discussed in relation to previous sightings in Cornwall.
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Biomass and compositional changes occur in chalk grassland turves exposed to elevated CO2 for two seasons in FACE. Warwick, K. R.; Taylor, G.; Blum, H. Global Change Biology. 1998. v 4(4) p.375-385
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Rhizomatous Lotus corniculatus L. III. Introgression of rhizomes into autogamous germplasm. Nualsri, C. ; Beuselinck, P.R.; Steiner, J.J. Crop science. 1998. v. 38 (2), p. 503-509.
Introduction of genes for rhizomes from wild Lotus corniculatus L. germplasm into domesticated germplasm may be an important step towards improving persistence of cultivated L. corniculatus, normally a cross-pollinated herbage crop. This study was initiated to determine if rhizomes could be transferred to a L. corniculatus germplasm that sexually reproduces via autogamy. Autogamy is an unusual reproductive expression in this typically self-incompatible species. Compatibility was high between the autogamous germplasm AG-S4 and five wild Moroccan accessions with rhizomes. Higher crossing success was obtained when AG-S4 was used as a maternal parent. Most seeds produced were normal in appearance and size and had high germination. The resulting F1 progeny were morphologically intermediate between the parents for size and shape of leaf and floral characters, but appeared more similar to their Moroccan parents. Differences between reciprocal crosses were not evident. Hybridity of progeny was confirmed by random amplified polymorphic DNA (RAPD) analysis using eight primers. Fertility of F1 progeny was low relative to their parents. Meiosis of parental genotypes was characterized by a high frequency of bivalents, but the meiotic behavior or their F1 hybrids was more irregular. The frequency of univalents varied from 0 to 8 with an average 2.4 per cell, indicating homology of chromosomes between AG-S4 and Moroccan accessions was not complete. Rhizomes were successfully expressed in F1 hybrids and a small number were round to also be autogamous. The autogamous hybrids will be important tools to elucidate the inheritance of rhizomes in L. corniculatus. Selection among the hybrids could lead to autogamous, rhizomatous cultivars of L. corniculatus.
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Facilitative effect of Lotus tenuis on Paspalum dilatatum in a lowland grassland of Argentina. Quinos, P.M. ; Insausti, P.; Soriano, A. Oecologia. 1998. v. 114 (3), p. 427-431.
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Regulation of the plant aspartate aminotransferase P2 gene during nodule development. Reynolds, P.H.S. ; Mett, V.; Vincze, E.; Podivinsky, E. In: Biological nitrogen fixation for the 21st century : proceedings of the 11th International Congress on Nitrogen Fixation, Institut Pasteur, Paris, France, July 20-25, 1997, p. 235-236.
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HAR1, an incomplete dominant mutation in Lotus japonicus, confers aberrant root development and an unusual HyperNodulation Response (HNR). Szczyglowski, K. ; Wopereis, J.; Dazzo, F.B.; deBruijn, F.J. In: Biological nitrogen fixation for the 21st century : proceedings of the 11th International Congress on Nitrogen Fixation, Institut Pasteur, Paris, France, July 20-25, 1997, p. 305-306.
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Research strategy in solving problems on extending the nitrogen fixation ability to major neoleguminous plants 1. Molecular genetic approaches to symbiotic nitrogen fixation using Lotus japonicus. Kawaguchi, M. Japanese Journal of Soil Science and Plant Nutrition. 1998. V 69(3):.310-315.
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Fusions between green fluorescent protein and beta -glucuronidase as sensitive and vital bifunctional reporters in plants. Quaedvlieg, N. E. M.; Schlaman, H. R. M.; Admiraal, P. C.; Wijting, S. E.; Stougaard, J.; Spaink, H. P. Plant Molecular Biology. 1998. V 37:715-727.
By fusing the genes encoding green fluorescent protein (GFP) and beta -glucuronidase (GUS) a set of bifunctional reporter constructs were created that are optimized for use in transient and stable expression studies in plants. This approach makes it possible to combine the advantage of GUS, its high sensitivity in histochemical staining, with the advantages of GFP as a vital marker. The fusion proteins were functional in transient expression studies in tobacco using either DNA bombardment or potato virus X as a vector, and in stably transformed Arabidopsis thaliana and Lotus japonicus plants. The results show that high level of expression does not interfere with efficient stable transformation in A. thaliana and L. japonicus. Using confocal laser scanning microscopy it was shown that the fusion constructs are suitable for promoter expression studies in all organs of living plants, including root nodules. The use of these reporter constructs in the model legume L. japonicus offers possibilities for the study of the root nodulation process.
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The Lotus japonicus LjNOD70 nodulin gene encodes a protein with similarities to transporters. Szczyglowski, K.; Kapranov, P.; Hamburger, D.; Bruijn, F. J. de. Plant Molecular Biology. 1998. V 37:651-661.
A novel nodule-specific gene, LjNOD70, associated with late stages in L. japonicus nodule development and/or functioning was characterized (GenBank accession number AF031243 and the related expressed sequence tag (126K15) AF031244). The LjNOD70 gene is a member of a small family of closely related L. japonicus genes. Two major mRNA species corresponding to the LjNOD70 gene were identified in nodules and shown to be the result of a mechanism resembling alternative splicing. The longer, presumably unspliced, mRNA species was shown to contain a single open reading frame (ORF), encoding a polytopic hydrophobic protein, LjN70, with a predicted molecular mass of 70 kDa. The second, presumably spliced, mRNA species was shown to be less abundant in nodules. The absence of the presumptive 'intron' divided the reading frame into an upstream and a downstream ORF encoding the partial N- and C-terminal regions of the LjN70 protein, respectively. The predicted amino acid sequence of nodulin LjN70 revealed structural features characteristic of transport proteins, and shared similarity with the oxalate/formate exchange protein of Oxalobacter formigenes. It is proposed that the L. japonicus LjNOD70 gene family encodes nodule-specific transport proteins, which may have evolved as a result of exon-intron shuffling.
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Genetic variation and gene flow in Alpine diploid and tetraploid populations of Lotus (L. alpinus (D.C.) Schleicher/L. corniculatus L.). I. Insights from morphological and allozyme markers. Gauthier, P.; Lumaret, R.; Bedecarrats, A. Heredity. 1998. V 80:683-693.
The altitudinal distribution, morphology, phenology and allozyme polymorphism at 12 loci were studied in diploid and tetraploid populations of Lotus growing at over 1800 m in the French Alps to clarify relationships between these cytotypes. In some previous studies these diploid and tetraploid cytotypes have been identified as the distinct species L. alpinus and L. corniculatus, respectively. In general, diploids occurred at higher elevation than tetraploids, although some sites at intermediate elevation contained both cytotypes, diploids predominating in the upper part and tetraploids in the lower part of the contact area. Evidence for an autopolyploid origin of the tetraploids was provided by tetrasomic inheritance at two enzyme loci, although no tetravalents were observed at meiosis. Diploid and tetraploid plants shared morphological traits distinct from those of other Lotus species and showed differences in size, which may be attributable to chromosome doubling. The diploid cytotype, L. alpinus, may thus be the ancestor of the Alpine tetraploids. Both cytotypes showed nearly identical suites of alleles at all loci and very similar genetic parameters, except for heterozygosity, which was higher in the tetraploid plants. However, the occurrence of few alleles specific to each ploidy level indicated limited gene flow between cytotypes, probably as a result of spatial segregation and variation in flowering time. Of the individuals in a tetraploid population, 25% showed morphological traits similar to those observed in L. corniculatus, suggesting genetic introgression between the two tetraploid species.
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Genetic variation and gene flow in Alpine diploid and tetraploid populations of Lotus (L. alpinus (D.C.) Schleicher/L. corniculatus L.). II. Insights from RFLP of chloroplast DNA. Gauthier, P.; Lumaret, R.; Bedecarrats, A. Heredity. 1998. V 80:694-701.
RFLP of chloroplast DNA was studied in two diploid (2x) and five tetraploid (4x) populations of Lotus alpinus in the French Alps. This was compared with four non-Alpine populations and two cultivars of Lotus corniculatus (4x) introduced to the Alpine valleys. Based on the 13 site and 11 length mutations detected, seven distinct haplotypes were identified, which clustered in two groups, corresponding to the two Lotus species. With only one exception, the diploid and the tetraploid L. alpinus plants had the same haplotype. This is to be expected, because morphological variation and tetrasomic inheritance suggest that the tetraploids were derived from the diploids by autopolyploidy. In L. corniculatus, two very similar haplotypes were found in the natural very distant populations. In contrast, the chloroplast DNA (ctDNA) haplotypes of the two cultivars differed considerably from each other and were more related to those observed in L. alpinus, suggesting that these cultivars may be derived maternally from L. alpinus individuals. In one tetraploid L. alpinus population, a single ctDNA haplotype was identified. As this haplotype was related to those observed in the L. corniculatus group, local genetic introgression may have occurred between 4x L. alpinus plants and cultivated L. corniculatus.
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Composted sawdust as a carrier for Bradyrhizobium, Rhizobium and Azospirillum in crop inoculation. Kostov, O.; Lynch, J.M. World journal of microbiology & biotechnology. 1998. v. 14:389-397.
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Preliminary studies of the effects of pre-emergence herbicides on the establishment of injurious weed and wildflower species. Pywell, R.F.; Nowakowski, M.; Walker, K.J.; Barratt, D.; Sparks, T.H. Weed seedbanks: determination, dynamics and manipulation. 23-24 March 1998, St. Catherine's College, Oxford, p. 173-178.
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Nodule organogenesis and symbiotic mutants of the model legume Lotus japonicus. Szczyglowski, K. ; Shaw, R.S.; Wopereis, J.; Copeland, S.; Hamburger, D.; Kasiborski, B.; Dazzo, F.B.; De Bruijn, F.J. de. Molecular plant-microbe interactions. 1998. v. 11(7), p. 684-697.
A detailed microscopical analysis of the morphological features that distinguish different developmental stages of nodule organogenesis in wild-type Lotus japonicus ecotype Gifu B-129-S9 plants was performed, to provide the necessary framework for the evaluation of altered phenotypes of L. japonicus symbiotic mutants. Subsequently, chemical ethyl methanesulfonate (EMS) mutagenesis of L. japonicus was carried out. The analysis of approximately 3,000 M1 plants and their progeny yielded 20 stable L. japonicus symbiotic variants, consisting of at least 14 different symbiosis-associated loci or complementation groups. Moreover, a mutation affecting L. japonicus root development was identified that also conferred a hypernodulation response when a line carrying the corresponding allele (LjEMS102) was inoculated with rhizobia. The phenotype of the LjEMS102 line was characterized by the presence of nodule structures covering almost the entire root length (Nod++), and by a concomitant inhibition of both root and stem growth. A mutation in a single nuclear gene was shown to be responsible for both root and symbiotic phenotypes observed in the L. japonicus LjEMS102 line, suggesting that (a) common mechanism(s) regulating root development and nodule formation exists in legumes.
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Soil acidification through carbon cycling in legumes: a pot experiment examining the contributions from white clover, lotus, caucasian clover, and lucerne. Monaghan, R. M.; Morrison, J. D.; Sinclair, A. G. New Zealand Journal of Agricultural Research. 1998. V 41:243-250.
Soil acidification, induced by the growth of four legume species (white clover (Trifolium repens), lotus (Lotus), lucerne (Medicago sativa), or caucasian clover (Trifolium)), was examined in a glasshouse pot trial at initial soil pH levels of either 4.5, 5.0, or 5.5. White clover and lotus out-yielded lucerne and caucasian clover at all soil pH levels, particularly at the lowest level of pH 4.5. The acidity produced as a result of this legume growth was shown to approximately correspond to the removal of excess cation over anion nutrients by the plants. Averaged over all three soil pH levels, plant excess cation concentrations decreased in the order: white clover > caucasian clover > lucerne > lotus. With the exception of white clover, there was no evidence of any consistent change in excess cation concentrations as soil pH decreased, indicating that the rate of excess cation removal did not decrease as soil pH declined. Although white clover was shown to have a higher excess cation concentration than the other three legumes, plant yield was the major determinant of legume-induced soil acidification, rather than legume species excess cation concentration.
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Lotus corniculatus nodulation specificity is changed by the presence of a soybean lectin gene. Rhijn, P. van; Goldberg, R. B.; Hirsch, A. M. Plant Cell. 1998. V 10:1233-1249.
Plant lectins have been implicated as playing an important role in mediating recognition and specificity in the Rhizobium-legume nitrogen-fixing symbiosis. To test this hypothesis, the soyabean lectin gene Le1 was introduced either behind its own promoter or behind the cauliflower mosaic virus 35S promoter into Lotus corniculatus, which is nodulated by R. loti. Nodule-like outgrowths developed on transgenic L. corniculatus plant roots in response to Bradyrhizobium japonicum, which nodulates soyabean and not Lotus spp. Soyabean lectin was properly targeted to L. corniculatus root hairs, and although infection threads formed, they aborted in epidermal or hypodermal cells. Mutation of the lectin sugar binding site abolished infection thread formation and nodulation. Incubation of bradyrhizobia in the nodulation (nod) gene-inducing flavonoid genistein increased the number of nodule-like outgrowths on transgenic L. corniculatus roots. Studies of bacterial mutants, however, suggest that a component of the exopolysaccharide surface of B. japonicum, rather than Nod factor, is required for extension of host range to the transgenic L. corniculatus plants.
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Mycorrhiza mutants of Lotus japonicus define genetically independent steps during symbiotic infection. Wegel, E.; Schauser, L.; Sandal, N.; Stougaard, J.; Parniske, M. Molecular Plant-Microbe Interactions. 1998. V 11:933-936.
Four nodulation mutants of L. japonicus affected in 3 different genetic loci blocked infection by G. intraradices within rhizodermal cells where abnormal deformations of hyphae occurred. Rare successful infections led to the formation of arbuscules. It is suggested that the affected plant genes are essential during the early infection process, but are dispensable for later developmental stages.
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Diurnal and seasonal osmotic potential changes in Lotus creticus creticus plants grown under saline stress. Sanchez-Blanco, M. J.; Morales, M. A.; Torrecillas, A.; Alarcon, J. J. Plant Science (Limerick). 1998. V136: 1-10.
Lotus creticus creticus plants grown in a greenhouse were exposed to 0, 70 and 140 mM NaCl for 4 months (September-December). Salinity caused a reduction in total dry weight of Lotus plants treated with 140 mM NaCl, whereas no significant effects on growth were observed with 70 mM NaCl. Predawn leaf water potential and predawn leaf osmotic potential showed constant values in control plants during all experiment, whereas a decrease of both parameters was observed between September and October for the saline treatments. The relative contribution of passive (dehydration) versus active mechanisms (osmotic adjustment) involved in seasonal leaf osmotic potential changes were determined. Seasonal decreases of the osmotic potential at full turgor in the treated plants showed the capacity for osmotic adjustment by accumulation of Na+ and Cl-1, because the accumulation of organic solutes due to salts was not consistent. In plants treated with 70 mM NaCl, the seasonal changes of the osmotic potential were produced by net solute accumulation, because the dehydration contribution was negligible. In plants treated with 140 mM NaCl, the seasonal changes of the osmotic potential were caused by ion accumulation, but also by tissue dehydration. At the end of the salinization period (December), a possible diurnal adaptation in water relations was also considered. The dehydration was the major mechanism involved in diurnal changes of leaf osmotic potential, and only at the highest salinity level some diurnal osmotic adjustment could be observed. In conclusion, the osmotic adjustment in Lotus might be a beneficial trait when the plants are treated with moderate levels of salinity (70 mM NaCl). At higher salinity (140 mM NaCl), the high absorption and accumulation of ions causes important toxic effects and induces leaf tissue dehydration.
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Study on the effectiveness of growing Lotus corniculatus as an interplant crop in a hawthorn orchard. Ding YuChuan; Yu XiaoQiou. China Fruits. 1998. 1:26-28.
Intercropping with L. corniculatus was investigated in a hawthorn orchard with sandy soil (in Shanxi, China). Tree spacing was 1 x 2 m, and L. corniculatus was sown in the row spaces. Intercropping increased soil organic content by 27.6%, and soil N, P and K increased by 3.3, 13.6 and 10.6%, respectively. Soil temperature was reduced by 1.5 deg C. Hawthorn production, fruit weight, and fruit pectin and ascorbic acid content increased under intercropping.
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Plant cold acclimation, hardiness, and winter injury in response to bare soil and groundcover-based nursery field management systems. Calkins, J.B.; Swanson, B.T. Journal of environmental horticulture. 1998. v. 16 (2), 82-89.
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Soluble acid invertase activity in leaves is independent of species differences in leaf carbohydrates, diurnal sugar profiles and paths of phloem loading. Kingston-Smith, A.H.; Galtier, N.; Pollock, C.J.; Foyer, C.H. The New phytologist. 1998. 139:283-292.
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Methods for establishing legumes on sandy soils. Rehm, G.W.; Sheaffer, C.C.; Martin, N.P.; Becker, R.L. Journal of production agriculture. 1998. 11:108-112.
Crop establishment is a major concern for producers who grow legumes on sandy soils. This study was conducted on a Verndale sandy loam (coarse-loamy, mixed Udic Argiboroll) to evaluate the impact of five methods of establishment on the production of four legumes (alfalfa [Medicago sativa L.], birdsfoot trefoil [Lotus corniculatus L.], cicer milkvetch [Astragalus cicer L.], red clover [Trifolium pratense L.]). Methods varied from the use of a clean, prepared seedbed to no-till seeding into small grain stubble. The study was initiated in 1991 and repeated in 1992. Yields from spring seedings were measured in the year of establishment. Dry matter yields were also measured for two residual years following establishment. Stand counts were taken in the fall of 1992. Yields of all legumes measured in the year of establishment were generally higher when there was no competition from a companion crop. In general, yields of alfalfa and red clover were equal but higher than yields of birdsfoot trefoil and cicer milkvetch when all establishment methods are considered. Stand counts showed that all establishment methods produced an acceptable stand of all legumes. Measured stand, however, was not directly related to forage yield. The results of this study show that these are several methods that can be used to successfully establish legumes on sandy soils. Choices for individual forage producers will be highly dependent on erosion potential and crops grown for the total farming system.
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Phytoextraction for soil remediation. Grath, S.P. In: Plants that hyperaccumulate heavy metals : their role in phytoremediation, microbiology, archaeology, mineral exploration and phytomining, p. 261-287.
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Tolerance to herbicides of ground cover species for New Zealand orchards. Harrington, K. C.; Rahman, A. Plant Protection Quarterly. 1998 13:111-116.
Herbicide tolerance studies were conducted on 8 species with potential for ground cover use in New Zealand orchards. Festuca rubra and F. longifolia tolerated a wide range of grass killing herbicides and could be easily cleared of weeds. Weeds in Trifolium repens could be controlled by haloxyfop, 2,4D, MCPA and glyphosate, while paraquat, diquat, simazine and haloxyfop could be used in Lotus pedunculatus (L. uliginosus) swards. Dichondra micrantha was sufficiently tolerant of tribenuron, clopyralid, glyphosate, glufosinate and paraquat/diquat to make it a suitable cover crop. Hydrocotyle heteromeria and Centella uniflora tolerated several knockdown herbicides. However, the range of herbicides tolerated by Agrostis castellana would not allow easy removal of grass weeds. The potential of cover crops in orchards for weed control is discussed.
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Rhizomatous Lotus corniculatus: IV. Inheritance of rhizomes. Nualsri, C.; Beuselinck,: R. Crop Science. 1998. 38:1175-1179.
Rhizome production has been transferred from wild germplasm of Lotus corniculatus (broadleafed birdsfoot trefoil) into domesticated cultivars and autogamous germplasm. The objective of this study was to determine the inheritance of rhizomes in L. corniculatus. Crosses were made between AG-S4, an autogamous, non-rhizomatous germplasm and two rhizomatous accessions from Morocco, G31276 and G31317. Two autogamous progeny from each cross (verified as F1 hybrids by morphological, meiotic and RAPD markers) produced F2 seed and were reciprocally backcrossed (BC). After 40 wk growth in the greenhouse, F2 and BC progeny were scored for rhizome production. Plants failing to express rhizomes in the greenhouse were transplanted to the field at Columbia, Missouri, USA and reevaluated for presence or absence of rhizomes at the end of the growing season. Segregation ratios for rhizome expression were tested for goodness-of-fit by the Chi-square ( chi 2) test. The ratios of rhizome production in F2 and BCs to AG-S4 fit 3:1 and 1:1 rhizomatous:non-rhizomatous ratios, respectively, indicating that rhizome presence in L. corniculatus germplasms G31276 and G31317 is controlled by single dominant genes. The gene symbol R is proposed for rhizome expression.
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Effect of selection and temperature stress on the production of 2n gametes in Lotus tenuis. Negri, V.; Lemmi, G. Plant Breeding. 1998. 1174:345-349.
Five Lotus tenuis genotypes showing 2n pollen production greater than 5% and producing 4x progenies in 4x (male sterile Lotus corniculatus) x 2x crosses were found in different natural populations. Meiotic analyses of these plants showed some second metaphases with disoriented spindles, i.e. parallel and tripolar spindles which resulted in diads and triads, respectively. Because useful genes for winter growth and resistance to powdery mildew from L. tenuis can be introgressed into L. corniculatus via 2n gametes, a programme of selection was started to increase the occurrence of 2n gamete production in L. tenuis. Controlled crosses were performed between genotypes producing 2n gametes and the progenies were checked for 2n pollen production and meiotic aberration, following the same methodologies as used for the parental plants. Although in some progeny plants the frequency of 2n gamete production increased remarkably, the overall progeny level of 2n gamete production remained unchanged. This suggested that different genes for meiotic aberration exist in natural populations and/or differential seed-setting ability exists between genotypes. Diallel crosses between selected genotypes confirmed this hypothesis. Evaluation of 2n pollen production of clones grown under different temperature regimes (warm vs. temperate) showed that, in L. tenuis, the effects of genotype, temperature and genotype x temperature interaction are significant. In particular, high temperature increases the level of 2n gamete production in L. tenuis.
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Establishment and fecundity of Ostertagia circumcincta and Trichostrongylus colubriformis in lambs fed lotus (Lotus pedunculatus) or perennial ryegrass (Lolium perenne). Niezen, J. H.; Waghorn, G. C.; Charleston, W. A. G. Veterinary Parasitology. 1998. 78:13-21.
Forty-four 12- to 14-week-old Polled Dorset ram lambs, raised helminth free from birth, were used to investigate the effects of condensed tannins (CT) in lotus (Lotus pedunculatus (L. uliginosus)) on lamb growth and gastrointestinal nematode establishment and fecundity. CT bind to proteins in the rumen and increase the flow of protein to the intestines. Lambs were allocated to either a ryegrass (Lolium perenne) or lotus diet fed ad libitum, with or without twice daily drenching of polyethylene glycol (PEG) which binds with and deactivates the CT. One week after allocation to the diets, each lamb was infected per os with 10 000 Ostertagia circumcincta (Teladorsagia circumcincta) and 10 000 Trichostrongylus colubriformis larvae and slaughtered at 28 or 29 days pi. Lambs fed lotus had lower faecal egg counts (P<0.0001) and lower O. circumcincta burdens (P<0.001), fewer female O. circumcincta (P<0.001) and higher faecal dry matter (P<0.001) than lambs fed ryegrass, but numbers of T. colubriformis nematodes were not affected. This trial did not ascribe beneficial effects of L. pedunculatus to CT per se and the use of PEG does not seem appropriate to studies of parasitology.
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Phenylalanine ammonia lyase and syringaldazine oxidase activities in relation to lignin deposition in legumes. Bidlack, J. E.; Buxton, D. R.; Shibles, R. M.; Anderson, I. C. Recent Research Developments in Agronomy. 1997. 1:1-8.
Activities of phenylalanine ammonia-lyase (PAL) and syringaldazine oxidase (SO) in maturing stems of Medicago sativa, Lotus corniculatus and Trifolium pratense were determined at biweekly intervals in a greenhouse experiment. Cell wall and lignin content increased sigmoidally; PAL activity increased, peaked and decreased; and SO activity increased, peaked and levelled off or decreased as a function of regrowth days. Maximum deposition of lignin followed that of other cell wall components. Time of maximum PAL activity occurred 8 days before maximum lignin deposition in L. corniculatus and T. pratense and 3 days after maximum lignin deposition in M. sativa. Time of maximum PAL activity always preceded time of maximum SO activity. SO activity was correlated with lignin content in each species.
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Establishment of species in simple and complex mixtures in a permanent grassland of Festuca rubra-Agrostis tenuis using the herbicide glyphosate.<Original> Instalarea unor specii, amestecuri simple si complexe, pe o pajiste de Festuca rubra-Agrostis tenuis, erbicidata cu "gliyfosate". Rotar, I.; Rusu, M.; Prica, F. Notulae Botanicae, Horti Agrobotanici, Cluj-Napoca. 1996/1997. 26/27:99-107.
A sward on Mount Cindrel, Romania dominated by F. rubra and A. tenuis (A. capillaris) was treated with glyphosate to reduce the content of Nardus stricta and other weeds in autumn 1993 and direct sown with a mixture of Phleum pratense, Trifolium repens, Festuca rubra, Dactylis glomerata and Lotus corniculatus. Establishment and botanical composition were monitored for a further 3 years. Using this treatment, N. stricta and the weeds were largely replaced by P. pratense and F. rubra.
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Effect of sowing depth and soil water content on germination, development and initial growth of Lotus spp. on clay soils.<Original> Efecto de la profundidad de siembra y el contenido de agua del suelo en la germinacion, desarrollo y crecimiento inicial de Lotus spp., en suelos arcillosos. Acuna:, H.; Figueroa R., M.; Fuente A., A. de la Agro-Ciencia. 1997. 13:265-274.
In experiments in 1995/96 in Chillan, Chile, in pots under a shelter, L. corniculatus cv. Quimey, L. tenuis cv. Toba and L. uliginosus were sown at depths of 0. 0.5 or 1.0 cm with soil water at field capacity, 50% of usable soil water, or saturated or flooded soil. Germination percentage was greater in L. corniculatus than the other species regardless of conditions. Seed germination and seedling growth and development were 20% higher with sowing depths of 0.5 or 1.0 cm than with surface sowing. When temperatures were low (daily mean <10 deg C), saturated or flooded soil increased germination but had a negative effect on seedling development. When temperatures were higher (daily mean 20 deg C), these conditions had negative effects on germination and seedling development.
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Characterization of sites where six native and naturalized pasture species occur in the Dominio Humedo of Chile.<Original> Caracterizacion de sitios de crecimiento de seis especies pratenses nativas y naturalizadas del Dominio Humedo de Chile. Lopez C., I.; Balocchi L., O.; Lailhacar M.,:; Oyarzun S., C. Agro Sur. 1997. 25:62-80.
On the basis of sampling in spring and summer at sites dominated by each of Bromus valdivianus, Agrostis capillaris, Lotus uliginosus, Holcus lanatus, Anthoxanthum odoratum and Paspalum dasypleurus (P. dasypleurum) in the Dominio Humedo, a coastal fringe in central southern Chile, the differing site conditions (slope, soil chemistry and physical properties) required by each species are described.
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Effect of two methods of sowing Lotus tenuis on its establishment and forage production in grasslands in the flooding pampa of Argentina.<Original> Efecto de dos metodos de intersiembra de Lotus tenuis sobre su implantacion y sobre la produccion de forraje de pastizales del area ganadera del salado (Argentina). Colabelli, M.; Viviani Rossi, E. M. Avances en Produccion Animal. 1997. 22:123-128.
In a field trial in 1991-93 in the Buenos Aires region, L. tenuis was sown into grassland using a disc harrow with a seed drill attached or using a rotary seed drill. Plant establishment, plant density and dry matter production did not differ between sowing methods. However, dry matter production was 20-26% higher than in controls without oversowing of L. tenuis.
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Genetic manipulation of condensed tannins in higher plants: II. Analysis of birdsfoot trefoil plants harboring antisense dihydroflavonol reductase constructs. Robbins, M.P.; Bavage, A.D.; Strudwicke, C.; Morris, P. Plant physiology. 1998. 116:1133-1144.
We have produced and analyzed transgenic birdsfoot trefoil (Lotus corniculatus L.) plants harboring antisense dihydroflavonol reductase (AS-DFR) sequences. In initial experiments the effect of introducing three different antisense Antirrhinum majus L. DFR constructs into a single recipient genotype (S50) was assessed. There were no obvious effects on plant biomass, but levels of condensed tannins showed a statistical reduction in leaf, stem, and root tissues of some of the antisense lines. Transformation events were also found, which resulted in increased levels of condensed tannins. In subsequent experiments a detailed study of AS-DFR phenotypes was carried out in genotype S33 using pMAJ2 (an antisense construct comprising the 5' half of the A. majus cDNA). In this case, reduced tannin levels were found in leaf and stem tissues and in juvenile shoot tissues. Analysis of soluble flavonoids and isoflavonoids in tannin down-regulated shoot tissues indicated few obvious default products. When two S33 AS-DFR lines were outcrossed, there was an under representation of transgene sequences in progeny plants and no examples of inheritance of an antisense phenotype were observed. To our knowledge, this is the first report of the genetic manipulation of condensed tannin biosynthesis in higher plants.
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Symbiotic mutants deficient in nodule establishment identified after T-DNA transformation of Lotus japonicus. Schauser, L; Handberg, K.; Sandal, N.; Stiller, J.; Thykjaer, T.; Pajuelo, E.; Nielsen, A.; Stougaard, J. Molecular & general genetics: 1998. 259:414-423.
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Identification of Rhizobium loti by immunodiffusion.<Original> Identificacion de Rhizobium loti por inmunodifusion. Andreoli, Y. E.; Escuder, A. M. Q. de; Laich, F. S.; Gonzalez, N. S. Ciencia del Suelo. 1998. 16:16-19.
Percentage nodule occupation in Lotus tenuis and the competitive ability of Rhizobium loti strain 733 against native rhizobial populations in the soil are determined from field trial data. A randomized complete block design with twelve repetitions, with and without inoculation was used. Lotus seeds were inoculated with the selected strain 733. Samples were taken in autumn and spring: two samples in Balcarce and three in Maipu and Ayacucho. In the initial samples all the nodules from each plot were pooled for processing, however, for subsequent samples 10nodules were selected at random from each plot to obtain pure cultures. Rhizobial samples were analysed by immunodiffusion using antiserum 733. Serologic relationship reactions were classified as: total identity, partial identity and lack of identity. In Balcarce and Maipu no naturalized rhizobia were detected before sowing and the recovery of strain 733 after 18 months from inoculation was 78% and 69% respectively. In Ayacucho, with naturalized population of 5.7 x102 rhizobia g-1 of soil, the recovery was only 13%.
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Nodule parenchyma specific expression of the Sesbania rostrata early nodulin gene SrEnod2 is mediated by its 3' untranslated region. Chen Ru Jin; Silver, D. L.; Bruijn, F. J. de Plant Cell 1040 4651 1998 10 p.1585 1602.
The early nodulin Enod2 gene encodes a putative hydroxyproline rich cell wall protein and is expressed exclusively in the nodule parenchyma cell layer. The latter finding suggests that the Enod2 protein may contribute to the special morphological features of the nodule parenchyma and to the creation of an oxygen diffusion barrier. TheEnod2 gene of the stem nodulating legume Sesbania rostrata (SrEnod2) is induced specifically in roots by the plant hormone cytokinin, and this induction occurs at a post transcriptional level. In this paper, cis determinant(s) in the SrEnod2 locus responsible for nodule parenchyma specific expression are characterized, and it is shown that the 3' untranslated region (UTR) of the SrEnod2 gene is both required and sufficient for directing chimaeric reporter gene expression in the nodule parenchyma of transgenic Lotus corniculatus plants. Moreover, evidence is presented indicating that the SrEnod2 3' UTR does not act as a tissue specific enhancer element. By conducting a detailed deletion analysis of the 5' and 3' SrEnod2 regions, the minimal promoter of the SrEnod2 gene was delimited; the data suggested that the5' flanking sequences are not essential for nodule parenchyma specific expression. This finding is in contrast with the report that the 5'upstream region of the soyabean Enod2 gene directs nodule parenchyma specific expression, indicating that different mechanisms may be involved in regulating the expression of these two genes. It is definitively demonstrated that the cis element(s) for tissue specific expression are located within the 3' UTR of a plant nuclear gene.
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Symbiotic mutants deficient in nodule establishment identified after T DNA transformation of Lotus japonicus. Schauser, L.; Handberg, K.; Sandal, N.; Stiller, J.; Thykjaer, T.;Pajuelo, E.; Nielsen, A.; Stougaard, J. Molecular and General Genetics 1998. 259:414 423.
Nitrogen fixing root nodules develop on legumes as a result of an interaction between host plants and soil bacteria collectively referred to as rhizobia. The organogenic process resulting in nodule development is triggered by the bacterial microsymbiont, but genetically controlled by the host plant genome. Using T DNA insertion as a tool to identify novel plant genes that regulate nodule ontogeny, two putatively tagged symbiotic loci, Ljsym8 and Ljsym13, were identified in the diploid legume Lotus japonicus. The sym8 mutants are arrested during infection by the bacteria early in the developmental process. The sym13 mutants are arrested in the final stages of infection, and ineffective nodules are formed. These two plant mutant lines were identified in progeny from 1112 primary transformants obtained after Agrobacterium tumefaciens T DNA mediated transformation of L. japonicus and subsequent screening for defects in the symbiosis with Mesorhizobium loti. Additional non tagged mutants arrested at different developmental stages were also identified, and genetic complementation tests assigned all the mutations to 16 monogenic symbiotic loci segregating recessive mutant alleles. In the screen reported here independent symbiotic loci thus appeared with a frequency of approx equal to 1.5%, suggesting that a relatively large set of genes is required for the symbiotic interaction.
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The behaviour of some bird's foot trefoil (Lotus corniculatus L.) lines and varieties under conditions of the Suceava Plateau.<Original> Comportarea unor soiuri si linii de ghizdei (Lotus corniculatus L.) in conditiile podisului sucevei. Popovici, D.; Dragomir, N.; Ciubotariu, C.; Tonigar, D. S.C.A. Cercetari Agronomice in Moldova. 1996. 29:117 122.
In field trials in 1992 95 on the Suceava Plateau, Romania, 7 birdsfoot trefoil (L. corniculatus) lines created at the Timisoara Research Station were compared. Yields of up to 10.49 t dry matter/ha were obtained with cutting at flowering and 8.90 t with cutting at bud formation. Line TM 18 showed high persistence when cut at flowering.
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Strategy for catch crop development. II. Screening of species undersown in spring barley (Hordeum vulgare L.) with respect to catch crop growth and grain yield. Karlsson Strese, E. M.; Rydberg, I.; Becker, H. C.; Umaerus, M. Acta Agriculturae Scandinavica. Section B, Soil and Plant Science. 1998. 48:26 33.
Catch crops are recommended in Sweden as a way of decreasing nitrogen leaching from arable land. In six field trials a total of 118accessions from 39 species of Poaceae, Fabaceae and "other" families was tested as potential undersown catch crops. Barley yield was used as an indicator of competition. Establishment, height and green matter production, after harvest of the main crop and in December, were estimated for the accessions. In general, the Poaceae showed the highest green matter production, but they also had the largest negative influence on barley yield. With Poaceae as a catch crop, the barley yield was reduced by 5 15% for all species except for Agrostis tenuis, Festuca rubra and Holcus lanatus, but these three species had a lower green matter production than the average of all Poaceae. Of all Poaceae investigated, only one accession of Dactylis glomerata combined high green matter production with no negative influence on barley yield. In the Fabaceae and the "other" families, 11 out of 27 species had no negative influence on barley yield and of these Trifolium repens, Lotus corniculatus and Cichorium intybus had above average green matter production.
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Screening pasture species for shade tolerance. Devkota, N. R.; Kemp, P. D.; Hodgson, J. Proceedings Annual Conference Agronomy Society of New Zealand. 1997. 27:119 128.
In a field trial in 1996 in Palmerston North, New Zealand, Dactylis glomerata cv. Grasslands Wana, Lolium perenne cv. Grasslands Nui, Holcus lanatus cv. Massey Basyn, Plantago lanceolata cv. Grasslands Lancelot, Festuca arundinacea cv. Grasslands Advance, Agrostis capillaris cv. Grasslands Muster, Poa trivialis cv. Sabre, Trifolium repens cv. Grasslands Tahora, T. subterraneum cv. Karridale and Lotus uliginosus cv. Grasslands Maku grown in pots were shaded so that they received 14, 18, 27, 43 or 73% of the ambient photosynthetically active radiation (PAR). Tillering of all species decreased with increasing shade. However, mean tiller numbers per plant at the final cut under the lowest PAR were significantly higher for H. lanatus and D. glomerata than for the other grass species. L. uliginosus produced a higher number of branches under 14% ambient PAR than the other legumes.
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Transpiration rates and canopy conductance of Pinus radiata growing with different pasture understories in agroforestry systems. Miller, B. J.; Clinton, P. W.; Buchan, G. D.; Robson, A. B. <Editors> Dye, P. J. Tree Physiology. 1998 18 :575 582.
Forests at the limit: environmental constraints on forest function. A selection of papers presented at an international symposium held at Skukuza, Kruger National Park, South Africa, 11 17 May, 1997. Tree transpiration and canopy conductance were measured in Pinus radiata at two low rainfall sites of differing soil fertility in Canterbury, New Zealand. At the more fertile Lincoln site, the effects of two common pasture grasses (Dactylis glomerata and Lolium perenne)on tree transpiration and canopy conductance were also studied. At the less fertile Eyrewell Forest site, the effect of no understorey, and the effects of irrigation in combination with mixtures of grass(Agrostis capillaris and Holcus lanatus) or legume (Lotus pedunculatus (L. uliginosus)) species were determined. Tree xylem sap flux (Fd') was measured by the heat pulse method. Total canopy conductance to diffusion of water vapour (Gt) was calculated by inverting a simplified Penman Monteith model. The different treatment effects were modelled by the simple decaying exponential relationship Gt = Gtmax( bD), where D= air saturation deficit. At the Lincoln site, trees with an understorey of D. glomerata had lower Fd' and Gtmax than trees with an understory of L. perenne, although the sensitivity of Gt to increasing D (i.e., the value of b) did not differ between treatments. At the Eyrewell site, irrigation only increased Fd' in the absence of an understorey, whereas the presence of understorey vegetation, or lack of irrigation, or both, significantly reduced Gtmax and increased b. It is concluded that the selection of understorey species is critical in designing successful agroforestry systems for low rainfall areas.
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Selection of a super-growing legume root culture that permits controlled switching between root cloning and direct embryogenesis.
Akashi, R.; Hoffmann-Tsay, S.S.; and Hoffmann, F. Theoretical and applied genetics. May 1998. v. 96 (6/7), p. 758-764.
Root cultures, displaying vigorous growth and high embryogenic capacity, were established in the legume forage species Lotus corniculatus (bird's-foot trefoil). Root cloning as well as plant regeneration was achieved on hormone-free medium, in agitated culture in the dark or under stationary conditions in the light, respectively. These qualities of vigorous growth and regeneration faded with time in hormone-free culture, with slow-growing roots turning brown in color. Addition of the synthetic cytokinin-like hormone benzylaminopurine to the culture medium, however, re-established the aging tissue's capacity for somatic embryogenesis and plant formation. During continuous initiation of new cultures, it was possible to obtain one root culture (selected from 11 960 seeds at a 65% germination rate) which did not show the typical decline of qualities after prolonged proliferation but distinguished itself by displaying even faster growth and more vigorous embryogenic plant production on hormone-free medium. There was no decline since its initiation 9 months earlier. This super-growing root culture produces plants that show no morphological differences as compared to wild-type regenerants or seedlings. Roots, dissected from plantlets derived from super-root embryogenesis, expressed all the super-root qualities again when cultured in vitro. This is the first report on somatic embryogenesis from sustained root cultures without exogenous hormone application. Such a hormone-free, continuous root culture should provide a superior experimental system for genetic or developmental studies that might be sensitive to exogenous hormones, such as somaclonal variation in transgenesis or, since introduced in a legume species, nodulation in vitro.
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Transcription of a maize cDNA in Lotus corniculatus is regulated by T-DNA methylation and transgene copy number.
Bellucci, M.; Alpini, A.; Paolocci, F.; Damiani, F.; and Arcioni, S. Theoretical and Applied Genetics. 1999. 98:257-264.
Lotus corniculatus plants transformed with a maize cDNA (G1L) encoding a sulphur-rich gamma-zein were obtained by using two fusion genes: one with the CaMV 35S promoter, the other with the ribulose bisphosphate carboxylase small subunit (rbcS) promoter. The highest expression of G1L mRNA was found in plants transformed with G1L under the rbcS promoter. The steady state level of G1L mRNA in the leaves was generally directly correlated with the G1L copy number. However, due to a transcriptional block, no G1L mRNA was detected in some of the 35S-G1L multicopy transformants. Analyses with methylation-sensitive restriction enzymes revealed that the T-DNA of the silenced 35S-G1L transformants was methylated. T-DNA copy number, G1L silencing activity, and the state of methylation were strictly correlated in primary transformants. A cross between two 35S-G1L transformed plants, one (S) with the T-DNA methylated and the other (NS) without, showed that: (1) the methylated state of T-DNA passed through meiosis; and (2) when T-DNA copies from the two parents were combined in the progeny, the unmethylated T-DNA copies of parent NS became methylated at different levels and G1L mRNA production was dependent on the degree of methylation.
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Influence of different proportions of Lotus corniculatus in the diet of lambs on dags, flystrike and animal performance.
Leathwick, D.M.; and Atkinson, D.S. 1998. Wool Technology and Sheep Breeding 46:353-359.
The relationship was investigated between the number of days each fortnight spent grazing Lotus corniculatus or ryegrass / white clover and dags, flystrike and growth rates in lambs. Lambs which grazed lotus for 7 or more days each fortnight had significantly fewer dags (range, 86-154g; P<0.01).
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Nutritional and toxicological aspects of tannins.
Jean-Blain, C. 1998. Revue de Medecine Veterinaire 149:911-920.
Tannins are secondary metabolites of higher plants which play a prominent ecological role in their protection against natural predators. In feedstuffs, they usually act as antinutritional factors, decreasing feed consumption, protein efficiency and growth rate, particularly in monogastric animals. However, in ruminants, they can also exert a positive effect, by preventing frothy bloat, or by improving the nutritional utilization of alimentary nitrogen. Toxicity of tannins for non herbivorous monogastrics is low, and it can be demonstrated only in experimental conditions. Hydrolysable tannins, on the contrary, induce severe intoxications in ruminants and in the horse, The present review attempts to provide a current up-dated summary of these various aspects of tannins in animal nutrition.
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Production, faecal egg counts and worm burdens of ewe lambs which grazed six contrasting forages.
Niezen, J.H.; Robertson, H.A.; Waghorn, G.C.; Charleston, WAG. 1998. Veterinary Parasitology. 80:15-27.
Lambs were grazed on monospecific swards of one of six forages, some containing condensed tannins (CT); sulla (Hedysarum coronarium), Lotus corniculatus and L. pedunculatus and some without CT (lucerne (Medicago sativa), plantain (Plantago lanceolata) and a ryegrass/white clover pasture (Lolium perenne/Trifolium repens)) to evaluate effects of forage type on gastrointestinal nematode burdens, faecal egg count as well as liveweight gain (LWG), wool growth and dag formation over a 42-day period. A new allotment of feed was provided at seven-day intervals, and feed was available ad libitum. Total worm burdens in a pre-treatment slaughter group were ca. 22000 of which ca. 5000 were in the abomasum. Within each forage type, 10 of the 25 lambs (NP) were given an anthelmintic drench at 14-day intervals and the remaining 15 lambs (P) were not drenched. Daily gains of the NP lambs were double that of P lambs which grazed either L. corniculatus, lucerne or pasture, but parasitism had a lesser effect on performance of lambs which grazed sulla and L. pedunculatus. Plantain was not palatable and all lambs performed poorly. Highest daily gains in P lambs were for those which grazed sulla (175 g/day) and L. pedunculatus (160 g/day) with total worm burdens of 13100 and 23000 for the respective treatment groups. The other forages resulted in lower daily LWG in P lambs, and performance was not related to either worm burdens or worm species. This experiment has shown that, when sulla is fed, there is a reduction in worm burdens and faecal egg count (FEC), but with Maku lotus which also contains CT, the good level of performance was achieved despite in high worm burdens and FEC. The mechanisms by which these forages enable high levels of productivity in the face of a parasitism appear to differ, but both could be incorporated into forage feeding systems to reduce dependence on anthelmintic drenches.
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Rhizomatous birdsfoot trefoil exhibits a unique response to nitrogen-free conditions.
Kallenbach, R.L.; McGraw, R.L.; Beuselinck, P.R.; Balati, P.A. 1998. Agronomy Journal 90:709-713.
New genotypes of birdsfoot trefoil (Lotus corniculatus L.) from Morocco exhibit rhizomes, but little is known about their N2-fixation characteristics. Our objective was to evaluate the N2-fixation capacity of rhizomatous birdsfoot trefoil infested by native rhizobia or by strains used in commercial inoculants. An additional objective was to assess the N2-fixing potential of two Moroccan isolates, R.L. 5797 and R.L. 5758, on commercial cultivars of birdsfoot trefoil. Seedlings of 'Norcen', 'AU Dewey', and a Moroccan rhizomatous entry, designated 'RBRC', were individually inoculated with commercial strains BFT027, BFT028, BFT030, 1710-2, CB756, or strains R.L. 5797 or R.L. 5758. Control treatments were noninoculated seedlings with or without supplemental N. Surprisingly, the seedling mass of RBRC was equal (P > 0.05) for all treatments. Norcen exhibited its greatest seedling mass when inoculated with strain BFT027; AU Dewey, with strain R.L. 5797. The rhizomatous RBRC did not show specificity for native Moroccan isolates of rhizobia, but these isolates effectively nodulated the commercial cultivars of birdsfoot trefoil.
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Soil nitrogen and lodgepole pine seedling responses to five years of legume cover.
Kranabetter, J.M.; Trowbridge, R. 1998. The Forestry Chronicle 74:578-582.
Legumes were tested for their ability to increase soil N content and improve growth of lodgepole pine (Pinus contorta Dougl. ex Loud.) seedlings in west-central British Columbia. A trial with alsike clover at varying densities were tested at one site, while three legume species (alsike clover, birdsfoot trefoil, and white clover) were tested on a second site. After five years of legume cover, mineralizable N mass of the forest floor were 0.5 to 4.5 times those of controls. Total N of the forest floor more than doubled in the seeding density study compared with controls, but was insignificant in the multiple species study. Despite observed increases in soil nitrogen, lodgepole pine growth was not enhanced by the legume treatments. Factors such as N immobilization, root distribution, low S levels, and competition for B may have limited the response of lodgepole pine seedlings to additions of biologically fixed-N.
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Fusions between green fluorescent protein and beta-glucuronidase as sensitive and vital bifunctional reporters in plants.
Quaedvlieg, NEM.; Schlaman, HRM.; Admiraal, P.C.; Wijting, S.E.; Stougaard, J.; Spaink, H.P. 1998. Plant Molecular Biology 38:861-873.
By fusing the genes encoding green fluorescent protein (GFP) and beta-glucuronidase (GUS) we have created a set of bifunctional reporter constructs which are optimized for use in transient and stable expression studies in plants. This approach makes it possible to combine the advantage of GUS, its high sensitivity in histochemical staining, with the advantages of GFP as a vital marker. The fusion proteins were functional in transient expression studies in tobacco using either DNA bombardment or potato virus X as a vector, and in stably transformed Arabidopsis thaliana and Lotus japonicus plants. The results show that high level of expression does not interfere with efficient stable transformation in A. thaliana and L. japonicus. Using confocal laser scanning microscopy we show that the fusion constructs are very suitable for promoter expression studies in all organs of living plants, including root nodules. The use of these reporter constructs in the model legume L japonicus offers exciting new possibilities for the study of the root nodulation process.
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A field study of the effects of elevated CO2 on plant biomass and community structure in a calcareous grassland.
Leadley, P.W.; Niklaus, P.A.; Stocker, R.; Korner, C. 1999. Oecologia 118:39-49.
The effects of elevated CO2 on plant biomass and community structure have been studied for four seasons in a calcareous grassland in northwest Switzerland. This highly diverse, semi-natural plant community is dominated by the perennial grass Bromus erectus and is mown twice a year to maintain species composition. Plots of 1.3 m2 were exposed to ambient or elevated CO2 concentrations (n = 8) using a novel CO2 exposure technique, screen-aided CO2 control (SACC) starting in March 1994. In the 1st year of treatment, the annual harvested biomass (sum of aboveground biomass from mowings in June and October) was not significantly affected by elevated CO2. However, biomass increased significantly at elevated CO2 in the 2nd (+20%, P = 0.05), 3rd (+21%, P = 0.02) and 4th years (+29%, P = 0.02). There were no detectable differences in root biomass in the top 8 cm of soil between CO2 treatments on eight out of nine sampling dates. There were significant differences in CO2 responsiveness between functional groups (legumes, non-leguminous forbs, graminoids) in the 2nd (P = 0.07) and 3rd (P < 0.001) years of the study. The order of CO2 responsiveness among functional groups changed substantially from the 2nd to the 3rd year; for example, non-leguminous forbs had the smallest relative response in the 2nd year and the largest in the 3rd year. By the 3rd year of CO2 exposure, large species-specific differences in CO2 response had developed. For five important species or genera the order of responsiveness was Lotus corniculatus (+271%), Carex flacca (+249%), Bromus erectus (+ 33%), Sanguisorba minor (no significant CO2 effect), and six Trifolium species (a negative response that was not significant). The positive CO2 responses in Bromus and Carex were most closely related to increases in tiller number. Species richness was not affected by CO2 treatment, but species evenness increased under elevated CO2(modified Hill ratio; P = 0.03) in June of the 3rd year, resulting in a marginally significant increase in species diversity (Simpson's index; P = 0.09). This and other experiments with calcareous grassland plants show that elevated atmospheric CO2 concentrations can substantially alter the structure of calcareous grassland communities and may increase plant community biomass.
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The possible use of honeybee pollen loads in characterising vegetation.
Diaz-Losada, E.; Ricciardelli-D'Albore, G.; Saa-Otero, M.P. 1998. Grana 37:155-163.
Investigations of the composition of pollen loads collected by the honeybee in five areas of Galicia (NW Spain) and five areas of Umbria (Central Italy) have demonstrated that specific combinations of pollen grains in the corbicula pollen are related to the geographical origin of the pollen loads. Spanish and Italian pollen loads are clearly differentiated by the presence or absence of characteristic pollen grains. Large quantities of Eucalyptus, Cytisus scoparius-type, Genista, Lotus and Jasione are found in the Galician honeybee pollen whilst in the pollen from Umbria Onobrychis (Dipsacaceae), Trifolium pratense L., Cornus, Ulmus and Galega predominate. This information can be useful in understanding the ethology of the honeybee in biogeographically different areas.
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NolL of Rhizobium sp strain NGR234 is required for O-acetyltransferase activity.
Berck, S.; Perret, X.; Quesada-Vincens, D.; Prome, J.C.; Broughton, W.J.; Jabbouri, S. 1999. Journal of Bacteriology181:957-964.
Following (iso)flavonoid induction, nodulation genes of the symbiotic nitrogen-fixing bacterium Rhizobium sp. strain NGR234 elaborate a large family of lipooligosaccharidic Nod factors (NodNGR factors). When secreted into the rhizosphere of compatible legumes, these signal molecules initiate root hair deformation and nodule development. The nonreducing glucosamine residue of NodNGR factors are N acylated, N methylated, and mono- or biscarbamoylated, while position C-6 of the reducing extremity is fucosylated. This fucose residue is normally 2-O methylated and either sulfated or acetylated, Here we present an analysis of all acetylated NodNGR factors, which clearly shows that the acetate group may occupy position C-3 or C-4 of the fucose moiety. Disruption of the flavonoid-inducible nolL gene, which is preceded by a nod box, results in the synthesis of NodNGR factors that lack the 3-O- or 4-O-acetate groups. Interestingly, the nodulation capacity of the mutant NGR Omega nolL is not impaired, whereas introduction of the nod box::nolL construct into the related strain Rhizobium fredii USDA257 extends the host range of this bacterium to Calopogonium caeruleum, Leucaena leucocephala, and Lotus halophilus. Nod factors produced by a USDA257(pnolL) transconjugant were also acetylated. The nod box::nolL construct was also introduced into ANU265 (NGR234 cured of its symbiotic plasmid), along with extra copies of the nodD1 gene. When permeabilized, these cells possessed acetyltransferase activity, although crude extracts did not.
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The maize transcription factor Sn alters proanthocyanidin synthesis in transgenic Lotus corniculatus plants.
Damiani, F.; Paolocci, F.; Cluster, P.D.; Arcioni, S.; Tanner, G.J.; Joseph, R.G.; Li, Y.G.; de Majnik, J.; Larkin, P.J. 1999. Australian Journal of Plant Physiology 26:159-169.
Lotus corniculatus L. plants were transformed with Agrobacterium rhizogenes binary vector carrying the maize Sn regulatory gene driven by the 35S promoter. These plants showed modifications in the pattern of accumulation of proanthocyanidin (PA). All the transformed plants but one showed an increase in PA content in the root relative to control untransformed and control gus gene transformed plants (C). With respect to the PA accumulation in leaves, Sn transgenic plants were grouped in two classes: suppressed (S), that showed a consistent reduction of foliar PA content, and unsuppressed (U) that did not differ significantly from controls. Dihydroflavanol reductase (DFR) and leucocyanidin reductase (LAR) enzyme activities in S and U plant leaves mirrored the changes seen with foliar PA accumulation. LAR activity in the roots was consistent with the root PA levels. Mature Sn mRNA accumulated in the leaves of U plants, but not in leaves of S plants; however, leaves of both S and U plants were able to initiate Sn transcription. All Sn-transformed plants accumulated Sn message in root tissue. A possible negative interaction of Sn and an unidentified homologous endogene is proposed for explaining the behaviour of S plants.
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Companion crops for legume establishment: Forage yield, quality, and establishment success.
Wiersma, D.W.; Hoffman, P.C.; Mlynarek, M.J. 1999. Journal of Production Agriculture 12:116-122.
Alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus corniculatus L.) are the predominant forage legumes grown in the north central USA. Frequently these legumes are established with a companion crop to increase establishment year forage yield, reduce erosion, and suppress weeds. Information comparing forage yield, quality, and legume establishment using traditional companion crops of oat (Avena sativa L.) and oat+field pea (Pisum spp.) vs. annual ryegrass (Lolium spp.) and festulolium (Festulolium braunii K.A.) companion crops is limited. This study was conducted to evaluate establishment year forage yield, quality and legume establishment success using five establishment methods. Four companion crops (oat, oat + field pea, annual ryegrass, festulolium) were sown with either alfalfa, red clover, or birdsfoot trefoil at two Wisconsin locations in 1993 and 1994. Each legume species was also established alone. Plots were harvested initially based on companion crop maturity and additional summer harvests were made when legumes reached mid-late bud stage of growth. Establishment year forage yields were higher when a companion crop was used than when the legume was solo seeded. At Ashland, WI, oat + field pea companion crop-legume mixtures were highest yielding in both years, averaging 0.60 ton dry matter (DM)/acre more than solo seeded legumes in the establishment year. At Marshfield in 1993 annual ryegrass and festulolium companion crop-legume mixtures yielded 0.65 ton DM/acre more than oat or oat + field pea companion crop-legume mixtures and 1.05 ton DM/acre more than solo seeded legumes. All companion crop-legume mixtures were equal, but higher yielding than solo seeded legumes in 1994 at Marshfield. Birdsfoot trefoil plots were consistently lowest yielding at both locations, except Marshfield in 1994 when alfalfa growth was suppressed due to excess moisture. Forage quality was directly related to the legume content of the harvested forage. Among the companion crops, annual ryegrass and festulolium were most frequently the highest in CP and lowest in acid detergent fiber (ADF) and neutral detergent fiber (NDF). Using annual ryegrass or festulolium as a companion crop for legume establishment may enhance the overall quality of forage harvested in the seeding year as compared with oat companion crops, and will increase yield over solo seeded legumes. In years that favor aggressive ryegrass growth, legumes may establish more slowly and may not produce as much forage in the year after establishment.
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Effect of condensed tannins in birdsfoot trefoil (Lotus corniculatus) and sulla (Hedysarum coronarium) on body weight, carcass fat depth, and wool growth of lambs in New Zealand.
Douglas, G.B.; Stienezen, M.; Waghorn, G.C.; Foote, A.G.; Purchas, R.W. 1999. New Zealand Journal of Agricultural Research 42:55-64.
The effects of dietary condensed tannins (CT) on growth and performance of young male weaned lambs were measured during a 4-month grazing trial when either birdsfoot trefoil (Lotus corniculatus) cv. Grasslands Goldie or sulla (Hedysarum coronarium) cv. Grasslands Aokau were fed. Each legume was offered at restricted and an libitum allowances and the effects of CT were determined by giving half the lambs in each treatment a twice-daily drench of polyethylene glycol (PEG; mol wt 3350) to deactivate the CT. Both agronomic and animal performance characteristics were recorded. Sulla had higher (P < 0.01) pre-grazing herbage masses than birdsfoot trefoil (11.6 cf. 7.1 t DM ha-1) and sulla stem (<6 mm diam.) was eaten, in contrast to birdsfoot trefoil where stem was rejected by the lambs. The sulla and birdsfoot trefoil diets had similar protein concentrations in the DM, but sulla had a higher concentration of total CT (88 cf. 50 g CT kg-1 DM) and less structural carbohydrate (189 cf 328 g kg-1 DM) relative to birdsfoot trefoil. Lambs fed sulla had a similar performance to those grazing birdsfoot trefoil at restricted allowances, with average liveweight gains of 168 g d-1. At ad libitum allowances liveweight gains averaged 273 g d-1, but the CT in sulla reduced carcass weight from 21.2 kg (with PEG drenching) to 18.8 kg (P < 0.05). The CT in birdsfoot trefoil did not affect wool growth, liveweight gain, or carcass characteristics. The trial has shown that both forages are able to provide a high level of productivity, but the CT in sulla can be detrimental to carcass yield from young lambs given this forage as a sole diet for a prolonged period. However, the sulla produces substantially more DM and is better utilised by lambs than birdsfoot trefoil, and is able to sustain high levels of animal production per hectare.
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Assessing trace element uptake by vegetation on a coal fly ash landfill.
Woodbury, P.B.; Rubin, G.; McCune, D.C.; Weinstein, L.H.; Neuhauser, E.F. 1999. Water Air and Soil Pollution 111:271-286.
Improved methods are required to assess the risks posed by the uptake of potentially toxic elements such as selenium (Se), boron (B), and molybdenum (Mo) by vegetation on contaminated sites. In order to develop such methods and assess risk, vegetation was collected from two sites on a soil-capped coal fly ash landfill near Dunkirk, New York, during June of 1991 and June and August of 1992. The mean concentrations (mu g g-1) dry weight) of Se and Mo in the shoots did not exceed, respectively, 0.12 and 18.7 in bird's-foot trefoil (Lotus corniculatus L.), 0.06 and 12.1 in red clover (Trifolium pratense L.), 0.07 and 5.3 in timothy (Phleum pratense L.), and 0.09 and 2.2 in a mixture of grasses. These concentrations were greater than those in the same species harvested concurrently from a non-landfill site. The mean concentrations of B at the landfill ranged from 29 to 53 mu g g-1 in the legumes and from 2 to 11 mu g g-1 in the grasses, less than those at one non-landfill site but greater than those at another. Within the landfill, the concentration of Se in grasses was not correlated with the concentration of Se in soil and fly ash. The concentration of Se in grasses on both landfill sites was double that of grasses on the non-landfill site despite higher mean concentrations of Se in the upper soil (0-15 cm) on the non-landfill site. Therefore grass roots seem to be accessing Se from the ash by means of mass flow or other mechanisms. Based on our findings of significant variation in trace element uptake among species, harvests, and locations within sites, we recommend that contemporaneous transect sampling of at least two species be used to assess uptake of potentially toxic trace elements on landfills or other sites where contamination may occur.
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Seed production of Lotus uliginosus cv. Sharnae in response to plant population density.
Arango, N.; Jacobs, B.C.; Blumenthal, M.J. 1998. Australian Journal of Experimental Agriculture 38:837-842.
An experiment was carried out under irrigation in the field to determine the influence of plant population density (7.5, 15, 30 and 60 plants/m(2)) on growth, development and yield of the pasture legume Lotus uliginosus cv. Sharnae. Reproductive development (flowering, pod set and stages of pod development) was recorded from 79 days after establishment and harvests were taken on 3 occasions during pod development: 118, 138 and 158 days after establishment. At each harvest, plants were divided into leaf, stem and pods. The pods were further separated into maturity classes on the basis of colour, and seed number and weight measured for each class. Harvesting late (i.e. 158 days after establishment) maximised seed yield (113 g/m(2)) and seed quality (27% immature, green pods). Seed yield per unit area up to 158 days after establishment was relatively insensitive to plant population up to 60 plants/m(2) because the response of individual plants of lotus was highly plastic. At 158 days after establishment, dry matter per plant declined from 985 g at 7.5 plants/m(2) to 713 g at 60 plants/m(2). At the same time, seed number per plant and seed weight per plant were reduced from 27400 to 3230 seeds and from 15.5 to 1.65 g, respectively, across the range of population densities. Despite the lack of a clear optimum plant population for maximum seed yield, some aspects of seed quality declined at high population density. For example, single seed weight fell by about 10% from 0.563 mg and the proportion of the harvest contributed by seeds from immature pods rose from is to 33%, as population density increased from 7.5 and 60 plants/m(2) Seed quality and ease of management, rather than yield, may be the most important considerations when seed growers choose a sowing rate for a L. pedunculatus cv. Sharnae seed crop.
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Comparative performance of enterobacterial repetitive intragenic consensus polymerase chain reaction and lipopolysaccharide electrophoresis for the identification of Bradyrhizobium sp. (Lotus) strains.
Santamaria, M.; Agius, F.; Monza, J.; Gutierrez-Navarro, A.M.; Corzo, J. 1999. FEMS Microbiology Ecology 28:163-168.
We compared two methods for typing bacterial strains: electrophoretic lipopolysaccharide profiling and genomic fingerprinting by enterobacterial repetitive intragenic consensus-polymerase chain reaction. Our aim was to assess the relative utility of these techniques for identification of bradyrhizobia. A collection of Uruguayan Bradyrhizobium strains isolated from Lotus subbiflorus was selected to test both techniques in terms of their discriminating ability and ease of use. Both techniques were found to be equally discriminating and they classified the samples in the same way, although each method ascribed two strains to different groups. Genomic profiling of some strains required previous DNA purification, whereas this was found to be unnecessary for others. Lipopolysaccharide profiling was found to be easier and cheaper to perform, but was not useful for determination of the genetic relationship among the strains.
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Effect of Euphorbia esula on sheep rumen microbial activity and mass in vitro.
Roberts, J.L.; Olson, B.E. 1999. Journal of Chemical Ecology 25:297-314.
Most large herbivores avoid the invasive weed leafy spurge (Euphorbia esula L.), possibly because the plant contains secondary compounds including terpenoids and condensed tannins. On the other hand, E. esula has high nutritive value based on traditional measures such as crude protein, fiber, and dry matter disappearance and is consumed by sheep and goats. Our objective was to determine if material from undefoliated and previously defoliated E. esula shoots, mixed in different proportions with grass hay, adversely affects sheep rumen microbial activity and mass in vitro. Material from undefoliated and previously defoliated E. esula shoots was collected in June, July, and August 1994 near Grass Range, Montana. Usually, increasing levels of E. esula leaves and powers in the mixtures increased in vitro dry matter and neutral detergent fiber disappearances (DMD, NDFD), microbial gas production, and microbial purine concentrations. In contrast, increasing levels of E. esula stems in the mixtures decreased DMD, NDFD, microbial gas production, and microbial purine concentrations. Rumen microbial gas production and purine concentrations were higher with leaves from previously defoliated than undefoliated shoots. In contrast, rumen microbial gas production and DMD were lowest for stems from previously defoliated shoots; these responses correlated with high concentrations of condensed tannins in stems of previously defoliated plants. In early summer, the high nutritive value of E. esula appears to offset any potential negative effects associated with secondary compounds. In late summer, microbial response appears more sensitive to the presence of secondary compounds, when nutritive value of this plant is declining.
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The effects of antinutritional factors in legume seed and rapeseed on ruminant nutrition.
Hill, G.D.; Tamminga, S. 1998. Recent Advances of Research in Antinutritional Factors in Legume Seeds and Rapeseed 93:157-172.
Legume seeds and rapeseed meal provide an excellent potential source of protein supplement for the diet of ruminant animals. Unfortunately most legume seeds contain at least one antinutritional factor (ANF) such as alkaloids, lectins, tannins, and trypsin inhibitors. Because of detoxification in the rumen the negative effects of most ANF are less severe in ruminants than in non ruminants. Tannins at low levels may even show positive responses. Other legume seeds such as peanuts (Arachis hypogaea) and soya beans (Glycine max) can produce sever allergenic reactions in animals that are exposed to them. However, the literature indicates that only preruminant calves appear to have problems from the development of antigens to soya protein. Extracted rapeseed (Brassica spp) meal from some cultivars can contain significant levels of glucosinolates. These compounds, which are goitrogenic, are apparently not destroyed in the rumen. Trials have shown that they can affect both thyroxine and trioodiothyronine levels in the blood. Further, histological effects of goitrogenicity on the thyroid glands of rapeseed fed ruminant animals have been observed. This paper reviews recent developments on the impact of these factors on the nutrition of ruminant animals.
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Flooding tolerance in five populations of Lotus glaber Mill. (syn. Lotus tenuis Waldst. et. Kit.).
Vignolio, O.R.; Fernandez, O.N.; Maceira, N.O. 1999. Australian Journal of Agricultural Research 50:555-559.
Lotus glaber Mill. is a herbaceous legume, tolerant to flooding, that in a few decades has colonised the Flooding Pampa grasslands, an extensive wetland of 90 000 km(2) in central-east Argentina. In this study, the growth and nodulation of flooded plants in 5 local populations were evaluated. Thirty-day-old seedlings, grown in pots, were flooded outdoors during 4 months. Stem, leaf, and root biomass, as well as the number of nodules per plant, were lower in flooded plants than in non-flooded ones. In flooded plants, the submerged portions of stems were hypertrophied and populations differed in the proportion of plants with adventitious roots. Flood tolerance was significantly related to the proportion of plants with adventitious roots in stems of each population. A positive relationship was shown between the proportion of plants with adventitious root and number of nodules per plant. The plants were also tolerant of low temperatures and ice-sheeting of water. These results underline the importance of morphological adaptations related to the maintenance of plant functionality under flooding conditions. The results provide evidence of the existence of characters related to flooding tolerance, which should be taken into account in ecological studies and agronomic selection programs.
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Birdsfoot trefoil seed production: I. Crop-water requirements and response to irrigation.
Garcia-Diaz, C.A.; Steiner, J.J. 1999. Crop Science 39:775-783.
Forage legume seed crop reproduction can be modified by regulating soil-water availability. However, responses to water stress differ for each species, so a single optimal water management strategy is not available for all crops. The objectives of this research were to determine the crop-water requirements and the optimal water management conditions for birdsfoot trefoil (Lotus corniculatus L.) when grown for seed production under humid temperate marine climatic conditions of western Oregon, USA. The experiment was conducted on a Woodburn silt loam soil (fine-silty, mixed, mesic Aquultic Argixeroll) near Corvallis. Four single-application treatments varying in water depletion percentage (30 and 60% of field capacity) and replenishment amount (50 and 100% of amount depleted) were applied in 1994 and 1995. A low-stress treatment (LS) that received two to three applications per week of the amount depleted since the last application and a non-irrigated control were also investigated in 1994, 1995, and 1996. Increasing amounts of applied water resulted in increased seasonal crop evapotranspiration (ETc) with plants grown under low-stress having the greatest ETc and non-irrigated control plants the least (r = 0.91). The fraction of available soil water used by nonirrigated plants was greatest and the LS treatment the least of all treatments. For non-irrigated conditions, the crop-water requirement ranged from 240 to 255 mm. Soil-water conditions favorable for high vegetative development were opposite of the renditions for optimal seed yield water-use efficiency. Unlike other forage legume seed crops, birdsfoot trefoil grown under these conditions required minimal or no supplemental irrigation to achieve maximal seed yield.
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Development of N-2-fixing nodules on the wetland legume Lotus uliginosus exposed to conditions of flooding.
James, E.K.; Sprent, J.I. 1999. New Phytologist 142:219-231.
Seeds of the wetland legume, Lotus uliginosus, were germinated and grown in vermiculite which was either continuously flooded or well-drained. Plants from both treatments were infected by Mesorhizobium loti strain DUS341 via a 'classical' root hair pathway, although some flooded plants appeared to be infected via enlarged epidermal cells. Subsequent to infection by M. loti, nodule meristems, which had developed within the root outer cortex, were penetrated by infection threads that released bacteria into the meristematic cells. The infection threads and infection droplets were immunogold labelled with monoclonal antibodies (MAC265 and MAC236) that recognize epitopes (at approx. 155/170 and 170/210 kDa, respectively) on a glycoprotein component of the matrix that surrounded the bacteria within the threads or droplets. Although labelling of infection threads or infection droplets with MAC236 was stronger than that with MAC265, both antibodies strongly labelled material occluding intercellular spaces in the cortices of developing nodules that had not yet expressed nitrogenase (as determined by a lack of signal after immunogold labelling with an antibody raised against nitrogenase component II). After 60 d, nitrogenase activity, shoot and root dry weights, and nodule fresh weight per plant did not differ between the treatments. After a further 30 d submergence, the flooded stems developed extensive aerenchyma and there was profuse development of (nodulated) adventitious roots. Nodules also formed at the junction of adventitious roots and the subtending stem and these were connected vascularly to a small stalk of tissue which gave rise to both a nodule and an adventitious root. The hooded nodules had prominent lenticels, and possible air pathways from the atmosphere to the nitrogen-fixing bacteroids are discussed.
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Effects of disturbance and rabbit grazing on seedling recruitment of six mesic grassland species.
Edwards, G.R.; Crawley, M.J. 1999. Seed Science Research 9:145-156.
Seeds of two grass (Arrhenatherum elatius and Festuca rubra), two herb (Plantago lanceolata and Rumex acetosa) and two legume (Lotus corniculatus and Trifolium repens) species were sown in summer 1995 at four densities (no seed, 1000, 10 000 and 50 000 seeds m(-2)) into an established rabbit-grazed grassland given factorial combinations of rabbit fencing (with and without fences) and soil disturbance (with and without cultivation). On plots where no seeds were sown, only the species with persistent seed banks (P. lanceolata, L. corniculatus and T: repens) showed enhanced seedling emergence in response to disturbance. In disturbed soil, seedling densities of all species increased with increasing density of sown seeds, the effects of which were still evident for plant cover 2 years after seed sowing. In undisturbed vegetation, A. elatius, F. rubra, P. lanceolata and R. acetosa showed increased seedling densities following seed sowing; but in each case, there was an upper asymptote to seedling recruitment, presumably due to microsite limitation. Rabbit grazing reduced seedling densities, with this reduction being more pronounced with disturbance than without. However, the effect of rabbit grazing did not persist for some species; seedling mortality of R. acetosa, P. lanceolata, L. corniculatus and T: repens was higher on plots without rabbit grazing, so that plant densities of these species in summer 1996 and plant cover in summer 1997 were greater on grazed plots. The results indicate interactions between soil disturbance, propagule availability and herbivory, rather than disturbance alone, will play an important role in controlling seedling recruitment and species habitat distributions in grasslands.
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Seed production of Lotus uliginosus cv. Sharnae in response to plant population density.
Arango, N.; Jacobs, B.C.; Blumenthal, M.J. 1998. In: Australian journal of experimental agriculture. v 38 p. 837-842.
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Forage legumes as living mulches for trees in agroforestry practices - preliminary results.
Alley, J.L.; Garrett, H.E.; McGraw, R.L.; Dwyer, J.P.; Blanche, C.A. 1998. Agroforestry Systems 44:281-291.
Successful establishment and growth of tree seedlings in an agroforestry practice is dependent on the control of competing herbaceous vegetation. Conventional weed control methods (i.e., chemical, mechanical, and physical suppression) are effective but can be costly in terms of time, damage to non-target vegetation, or increased soil erosion. Alternatively, some living mulches can exclude undesirable vegetation, protect the soil, compete minimally with associated trees, and supplement soil nitrogen. In this study, small and large white clover (Trifolium repens L.), red clover (T. pratense L.), kura clover (T. ambiguum Bieb.), strawberry clover (T. fragiferum L.), birdsfoot trefoil (Lotus corniculatus L.), hairy vetch and 'AU Early' hairy vetch (Vicia villosa Roth) were selected for evaluation as living mulches. These species were established in 9 m x 9 m replicated plots along with two controls [tall fescue (Festuca arundinacea Schreb.) and bare soil kept vegetation free using glyphosate]. The controls represent 'high competition' and 'no competition', respectively. Eastern black walnut (Juglans nigra L.), honeylocust (Gleditsia triacanthos L.), and hybrid pitch x loblolly pine (Pinus rigida L. x P. taeda L.) seedlings were planted in association with each living mulch. Tree seedling heights and diameters were measured during the first two years and forage performance evaluated. All seedlings grew better in the absence of competition. Tall fescue greatly reduced the growth of hardwood seedlings. Red clover and ladino clover showed the greatest promise as living mulches for use with the hardwood and pine seedlings, respectively.
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The effect of condensed tannins in Lotus corniculatus upon reproductive efficiency and wool production in sheep during late summer and autumn.
Min, B.R.; McNabb, W.C.; Barry, T.N.; Kemp, P.D.; Waghorn, G.C.; McDonald, M.F. 1999. Journal of Agricultural Science 132:323-334.
A grazing experiment, conducted for 55 days (from 4 March to 29 April) in the late summer/autumn of 1997, at Massey University, Palmerston North, New Zealand, compared the reproductive efficiency and wool growth of ewes grazing Lotus corniculatus (birdsfoot trefoil) or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) dominant pasture (pasture). Half the ewes grazing each forage were given daily oral polyethylene glycol (PEG:molecular weight 3500) supplementation to inactivate the condensed tannins (CT) in lotus. A rotational grazing system with 200 mixed age ewes (54.2 +/- 0.88 kg/ewe; 50 ewes/treatment) was used. The effect of forage species and PEG supplementation upon voluntary feed intake (VFI), concentration of plasma metabolites, reproductive efficiency, wool production and wool characteristics was measured during two synchronized oestrous cycles. The ewes were restricted to maintenance feeding for the first 12 days of each oestrous cycle and then increased to ad libitum for the 6 days prior to and including ovulation. Lotus contained 17 g total CT/kg dry matter (DM) in the diet selected. There were only trace amounts of total CT in pasture. In vitro organic matter digestibility (OMD) was higher for lotus (0.82 v. 0.74) than for pasture, whilst lotus contained less nitrogen (N; 37.8 v. 44.5 g/kg OM). Mean ovulation rates (OR) for CT-acting and PEG sheep grazing pasture and lotus were respectively 1.33 v. 1.35 and 1.78 v. 1.56, with corresponding lambing percentages being 1.36 v. 1.36 and 1.70 v. 1.42. Fecundity (number of corpora lutea/ewe ovulating) was greater for ewes grazing lotus than pasture (P < 0.01), and tended to be greater for CT-acting than for PEG sheep grazing lotus(P = 0.06). In unsupplemented sheep, ewes grazing lotus had increased plasma concentrations of branched chain amino acids (BCAA; 57%) and essential amino acids (EAA; 52%) compared to ewes grazing pasture. In ewes grazing pasture, PEG administration had no effect on plasma concentrations of urea and free amino acids, VFI, reproductive efficiency and wool production. However, in sheep grazing lotus, plasma concentrations of urea were significantly lower and concentrations of most amino acids were significantly higher for CT-acting than for PEG supplemented ewes (CT not acting); there was no difference in VFI between these two groups. Compared to ewes grazing pasture, ewes grazing lotus had similar VFI but produced more wool with longer staples and thicker fibre diameter, with there being no effect of PEG supplementation. It was concluded that feeding lotus increased the efficiency of both reproduction and wool production without an increase in VFI, and that a possible cause was the action of CT in increasing plasma EAA and especially BCAA concentration.
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Germination and seedling growth at low temperature: comparisons of Lotus species and effects of selection and seed source in L. pedunculatus Cav.
Kelman, W.M.; Forrester, R.I. 1999. Australian Journal of Agricultural Research 50:969-975.
The association of seed size, type of life cycle (annual/perennial), and ploidy (diploid/tetraploid) with low temperature (5 degrees C), germination rate, and seedling growth was examined under controlled conditions in 9 Lotus species. Seeds harvested at 2 localities from 2 populations of L. pedunculatus, one selected for early flowering and the other unselected for flowering time, were included in the study to examine the influence of selection history and seed provenance on cold temperature germination rate and seedling growth. Seed size and ploidy level were not significant factors influencing germination rate of the Lotus species, but both seed size and life cycle had significant associations (P < 0.01) with seedling dry weight. Seed of the selected, early flowering population of L. pedunculatus germinated significantly faster than that of the unselected population (P < 0.01), and this difference was more pronounced in seed from the site where early flowering would confer advantages of better seed production and the potential for better persistence through seedling recruitment. A narrow-sense heritability estimate for the germination rate of L. pedunculatus was high at the 2 localities (0.84 +/- 0.17 and 0.65 +/- 0.16) and it was thus promising as a selection criterion for improved establishment. If interspecific hybridisation can be achieved between the annual and perennial species, a longer term prospect exists to utilise the high capacity of annual species to germinate and grow at low soil temperatures.
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Symbiotic effectiveness and ecological characterization of indigenous Rhizobium loti populations in Uruguay.
Baraibar, A.; Frioni, L.; Guedes, M.E.; Ljunggren, H. 1999. Pesquisa Agropecuaria Brasileira 34:1011-1017.
The objectives of this work were to describe the distribution, density and seasonal variation of the indigenous populations of Rhizobium loti in different Uruguayan soils and to determine the symbiotic effectiveness and stress tolerance factors of different isolates, both with the aim of obtaining selected strains to re-introduce as inoculants in Lotus pastures. R. loti was present in ten soils studied and their densities varied from year to year and within each soil. All the isolates nodulated Lotus corniculatus effectively. The nodules in Lotus pedunculatus and Lotus subbiflorus were small, red on the surface and ineffective in nitrogen fixation. The study of 50 isolates from the ten soils showed high variability in their symbiotic efficiency and tolerance to pH. The indigenous population was acid tolerant in culture medium (pH 4.5), 83% of them could grow at pH 4.5 in 3 days. This work showed that there was a great diversity between the strains of R. loti isolated from Uruguayan soils and supports the importance of selecting among them the most efficient and resistant strains to be included in the inoculants.
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Enhancement of botanical diversity of permanent grassland and impact on hay production in Environmentally Sensitive Areas in the UK.
Hopkins, A.; Pywell, R.F.; Peel, S.; Johnson, R.H.; Bowling, P.J. 1999. Grass and Forage Science 54:163-173.
Five methods for increasing the botanical diversity of permanent grassland, either by sowing site-specific species-rich grass/forb seed mixtures (strip-seeding; or over-sowing after sward disturbance by light harrowing, partial rotary cultivation or turf removal), or by introducing transplanted plug plants, were compared with a control treatment in replicated field experiments on six farm sites in Environmentally Sensitive Areas (ESAs) in England and Wales. Effects on herbage production under hay cutting in July and on botanical composition were recorded in the two subsequent years. Turf removal before sowing was the only treatment that significantly reduced herbage production; this treatment also had the greatest effect on increasing botanical diversity (to a mean of twenty-eight plant species per site compared with fifteen species for the control 2 years after sowing). The least successful establishment of sown species resulted from light harrowing before sowing; the rotary-cultivated and strip-seeded treatments increased species diversity, although by less than turf removal. Successful establishment of introduced species was greatest on sites having a low soil nutrient status. Species that established successfully from seed on most sites and treatments included the grasses Alopecurus pratensis, Cynosurus cristatus, Festuca rubra and Phleum pratense, and the forbs Achillea millefolium, Leucanthemum vulgare, Plantago lanceolata and Prunella vulgaris; in addition, Centaurea nigra, Hypochoeris radicata and Lotus corniculatus were also established by one or more methods on most sites, Lychnis flos-cuculi established successfully on mesotrophic sites, and Medicago lupulina on calcareous sites. Several species failed to establish at all or most sites where they were sown, e.g. Helianthemum nummularium, Pimpinella saxifraga and Rhinanthus minor. Most transplanted plug-plant species established successfully in the short term, but many failed to persist or their frequency in the sward remained low; exceptions included A. millefolium and P. lanceolata. The results are discussed in relation to the requirements for management to further the objectives of ESAs and agri-environmental schemes.
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Fusions between green fluorescent protein and beta-glucuronidase as sensitive and vital bifunctional reporters in plants [Erratum: Nov 1998, v. 38 (5), p. 917, 861-874.].
Quaedvlieg, N.E.M.; Schlaman, H.R.M.; Admiraal, P.C.; Wijting, S.E.; Stougaard, J.; Spaink, H.P. 1998. In: Plant molecular biology. 37:715-727.
By fusing the genes encoding green fluorescent protein (GFP) and beta-glucuronidase (GUS) we have created a set of bifunctional reporter constructs which are optimized for use in transient and stable expression studies in plants. This approach makes it possible to combine the advantage of GUS, its high sensitivity in histochemical staining, with the advantages of GFP as a vital marker. The fusion proteins were functional in transient expression studies in tobacco using either DNA bombardment or potato virus X as a vector, and in stably transformed Arabidopsis thaliana and Lotus japonicus plants. The results show that high level of expression does not interfere with efficient stable transformation in A. thaliana and L. japonicus. Using confocal laser scanning microscopy we show that the fusion constructs are very suitable for promoter expression studies in all organs of living plants, including root nodules. The use of these reporter constructs in the model legume L. japonicus offers exciting new possibilities for the study of the root nodulation process.
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Native vs. introduced bee flora: a palynological survey of honeys from Uruguay.
Daners, G.; Telleria, M.C. 1998. Journal of Apicultural Research 37:221-229.
A melissopalynological study was made to classify the botanical and geographical origin of 21 samples of commercial Uruguayan honeys. Sixty-six pollen types were found; 67% of the samples were unifloral. The taxa with the greatest frequencies (>15% of pollen in each sample) were Lotus corniculatus, Eucalyptus spp., Echium plantagineum, Scutia buxifolia and Baccharis spp. The taxa with highest occurrence (present in >85% of samples) were Eucalyptus spp., Trifolium pratense, L corniculatus, Schinus molle-type, Baccharis spp., Trifolium repens, Echium plantagineum, Eryngium spp., Scutia buxifolia, Salix humboldtiana and Poaceae. Forty-eight percent of the pollen taxa were endemic to the Americas; the majority of the other taxa were from Europe. The Uruguayan honeys we analysed typically contained pollen from the native Schinus molle type, Baccharis spp., Eryngium spp., Scutia buxifolia and Salix humboldtiana, together with pollen from the introduced Eucalyptus spp., L. corniculatus, T. pratense, T. repens and Echium plantagineum.
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Inheritance and expression of transgenes in T-2 and T-3 generations of Lotus corniculatus transformed using Agrobacterium tumefaciens.
Webb, K.J.; Humphreys, M.O.; Skot, L.; Gibbs, M.; Gatehouse, J. 1999. Euphytica 108:169-179.
The inheritance and expression of the reporter gene uidA, encoding beta-glucuronidase (GUS), was previously analysed in the T-1 generation of 25 independent transformed lines of Lotus corniculatus cv. Leo. In the work reported here, GUS activity in various tissues of seven of these lines was tested in the T-2 generation. Four representative lines were chosen for more detailed study in the T-3 generation. Lines 25 and 38 had multiple, independently segregating transgene inserts; lines 24 and 39 appeared to transmit one segregating transgene insert to their T-1 progeny, although transgene expression was low and was detected in fewer seedlings than expected in line 39. The uidA gene was inherited and expressed in seedlings of T-1, T-2 and T-3 generations of all four lines. In all lines, transgene expression varied between tissues, with more embryos than seedlings having detectable GUS activity. Studies in the T-2 generation showed that use of transgenic plants as female or male parents altered the frequency of expression of the transgene in progeny. By contrast, in the T-3 generation the use of transgenic plants as female or male parents did not effect either frequency of transmission, or expression of the transgene, in any of the four lines. Transgene inheritance was also similar among individual pods within flower heads and between individual flower heads.
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Shrub seedling recruitment in unburned Californian coastal sage scrub and adjacent grassland.
DeSimone, S.A.; Zedler, P.H. 1999. Ecology 80:2018-2032.
Shrub species of southern Californian coastal sage scrub recruit seedlings immediately after fire but also recruit in unburned coastal sage scrub stands and annual grasslands. We examined the influence of natural disturbances other than fire on shrub seedling establishment, especially the role of small-scale disturbance. Our goals were to determine: (1) whether seedling recruitment is associated with gaps in grassland, scrub, and grassland-scrub ecotones; (2) the identity of gap-creating agents; (3) the influences of biotic (vertebrates and ants) and abiotic (late spring moisture) disturbances on seedling establishment; and (4) whether disturbance effects vary spatially, both among and within (gap vs, nongap microsites) the three zones. We censused natural seedlings and vegetation gaps monthly in belt transects for two growing seasons and also measured seed banks at three 16-yr-old sites of adjacent grassland and coastal sage scrub. We initiated factorial experiments at one site to determine effects of animals, gaps, and late spring moisture on seed and seedling numbers. Gap-creating agents varied among the three zones, but seedlings were associated with gaps in each. Animals, especially small mammals, were important in creation and maintenance of gaps. Animal effects varied among but not within zones. Small mammals positively affected seedling recruitment in the grassland (germination on pocket gopher mounds) and negatively affected seed numbers of species with larger and multiple-seeded propagules in the ecotone and scrub; they created and/or maintained gaps in all three zones. Late spring moisture did not play an important role in shrub seedling recruitment in any zone. Because coastal sage shrub seedlings lose transpiring surfaces during drought, they may be less vulnerable than evergreen mediterranean shrubland species to the variability in both annual and seasonal extent of rainfall that is typical of mediterranean climates.
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Seed-to-seed allelopathic effects between two invaders of burned Pampa Grasslands.
Laterra, P.; Bazzalo, M.E. 1999. Weed Research 39:297-308.
The establishment of Lotus tenuis can interfere with colonization by Carduus acanthoides during the early post-burn recovery of Flooding Pampa grasslands. The purpose of this research was to determine the potential role of L. tenuis seeds as a source of allelopathic compounds involved in that interaction. Imbibed seeds of L. tenuis and aqueous leachates from them were bioassayed for their ability to inhibit germination and seedling growth of C. acanthoides, both on sterilized filter paper and on pasteurized soil as substrata. Germination and/or emergence of C, acanthoides were inhibited and root length was reduced on filter paper or soil, by both the presence of L, tenuis seeds and their leachate, at densities of L. tenuis near the maximum values observed in the field. Germination and seedling growth of C, acanthoides were less affected by the presence of L. tenuis seeds than by the addition of their leachate, and the presence of L. tenuis seeds or their leachate showed stronger effects on emergence of C, acanthoides from soil than on its germination on filter paper. Methods applied for leachate sterilization, ultrafiltration or autoclaving did not modify C, acanthoides responses. Neither the germination rate nor the root length of C, acanthoides seedlings were affected by solutions of polyethylene glycol with similar osmolarity to the leachates, We conclude that the release of inhibitory substances on to filter paper and into pot soil from imbibed L. tenuis seeds would be the mechanism responsible for the observed effects.
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Polyphenols and agriculture: beneficial effects of proanthocyanidins in forages.
Aerts, R.J.; Barry, T.N.; McNabb, W.C. 1999. Agriculture Ecosystems & Environment 75:1-12.
Proanthocyanidins (PA), also known as condensed tannins, belong to the oldest of plant secondary metabolites. These compounds are widespread in woody plants, but are also found in certain forages. Proanthocyanidins can exert effects in organisms because of their ability to complex with proteins. Forages containing moderate concentrations of PA (2-4% DM) can exert beneficial effects on protein metabolism in sheep, slowing degradation of dietary protein to ammonia by rumen micro-organisms and increasing protein outflow from the rumen, thus increasing absorption of amino acids in the small intestine of the animal. This was shown to result in increases in lactation, wool growth and liveweight gain, without changing voluntary feed intake. Dietary PA can also contribute to improved animal health by reducing the detrimental effects of internal parasites in sheep and the risk of bloat in cattle. In contrast, high dietary PA concentrations (6-12% DM) depress voluntary feed intake, digestive efficiency and animal productivity. Temperate forages containing PA, such as Lotus corniculatus and L. pedunculatus, will not persist in intensive grazing systems if continuously grazed (i,e. set stocked), especially in mixtures with perennial ryegrass and white clover and need to be grown as pure species and rotationally grazed. Nevertheless, inputs of these 'special purpose 'forages can increase sustainability and productivity in intensive grazing systems through increasing the efficiency of animal production, reducing urinary nitrogen (N) excretion and reducing chemical inputs as anthelmintics and as detergents used to control rumen bloat in cattle. Proanthocyanidins are derived from the flavonoid biosynthesis pathway, and knowledge is rapidly increasing about the molecular control of PA biosynthesis, These recent investigations may ultimately enable the expression by genetic engineering of increased levels of PA in the leaves of agriculturally important forage plants such as white clover and perennial rye grass, which will withstand continuous defoliation under grazing and currently contain only trace amounts of PA. This could potentially lead to the widespread use of PA in temperate grazing systems. Further consideration, should now be given to long-term adaptations in the animal, and to ecological effects on the soil ecosystem by PA and their degradation products excreted in animal faeces. More information is required in particular on the effects of PA on soil nitrification, ammonia volatilisation from soil, and nitrogen levels in the groundwater.
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Effect of competition on the responses of grasses and legumes to elevated atmospheric CO2 along a nitrogen gradient: differences between isolated plants, monocultures and multi-species mixtures.
Navas, M.L.; Garnier, E.; Austin, M.P.; Gifford, R.M. 1999. New Phytologist 143:323-331.
The responses to CO2 of perennial grasses (Danthonia richardsonii and Phalaris aquatica) and legumes (Lotus pedunculatus and Trifolium repens) were compared under controlled conditions for isolated plants, monoculture stands and mixed-species stands along a N gradient to test whether: plant-plant interactions between species in mixed stands changed with concentration of CO2; responses to CO2 of species in mixtures could be related to their responses as single stands; responses of mixtures to CO2 could be related to the responses of individual species to CO2 and to competition. Plants were grown for 60 d in sand, using nutrient solutions (six nitrate concentrations from 0.25 to 16 mM NO3), at ambient (c. 357 mu l l(-1)) or elevated CO2 (c. 712 mu l l(-1)). Species dominance in the mixtures depended more on the range of N than of CO2 concentration provided: T. repens and L. pedunculatus dominated at low concentrations of N; L. pedunculatus and P. aquatica performed better at high concentrations. Responses of species in mixtures to CO2 were related to their responses in monocultures but not to those of isolated plants. Species biomass proportions in mixtures under ambient CO2 determined the outcome of mixture responses to CO2 more than of individual species responses to CO2. These results emphasize the influence of plant-plant interactions on community responses to CO2, since mixture behaviour under elevated CO2 could not be scaled-up from responses by isolated plants in this experiment.
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Productivity, botanical composition, and nutritive value of swards including forage chicory.
Belesky, D.P.; Fedders, J.M.; Turner, K.E.; Ruckle, J.H. 1999.Agronomy Journal 91:450-456.
Pure stands of 'Grasslands Puna' chicory (Cichorium intybus L.) are productive and responsive to N fertilization in the eastern USA. We conducted a field experiment for 3 yr to investigate productivity and nutritive value of swards including chicory, orchardgrass (Dactylis glomerata L.), and birdsfoot trefoil (Lotus corniculatus L,) as a function of clipping frequency (3- and 6-wk intervals). Each treatment was replicated three times on an upland site of Dekalb series soil (loamy-skeletal, mixed, subactive, mesic Typic Dystrochrept). Modest rates of N, P, and K were applied annually. Herbage mass, botanical composition, in vitro organic matter disappearance (IVOMD), and crude protein (CP) were determined. Cumulative herbage yield was not influenced by initial sward composition with chicory, chicory-orchardgrass, and chicory-orchardgrass-trefoil averaging 6.8 Mg ha(-1) during a growing season. Clipping frequency influenced yield with canopies clipped at 6-wk intervals producing 26% more herbage than those clipped at 3-wk intervals. Growth rates of canopies clipped at 6-wk intervals averaged 51 kg ha(-1) d(-1) early in the growing season, suggesting that swards including chicory would be responsive to nutrient inputs and where rapid herbage regrowth and nutrient use by the growing crop are needed. Chicory declined in swards with time, regardless of initial sward composition or clipping frequency, Fluctuations in IVOMD and CP were related to changes in sward composition arising from the interaction of time and clipping frequency, Including orchardgrass and trefoil retarded invasion of less desirable species and so provided a means to control overall sward productivity and herbage composition.
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Sodium sulphite effects on recovery and composition of detergent fibre and lignin from forage legumes varying in levels of proanthocyanidins.
Krueger, C.G.; Albrecht, K.A.; Reed, J.D.; Bures, E.J.; Owens, V.N. 1999. Journal of the Science of Food and Agriculture 79:1351-1356.
Alfalfa (Medicago sativa L), red clover (Trifolium pratense L), birdsfoot trefoil (Lotus corniculatus L), sainfoin (Onobrychis viciifolia Scop), crownvetch (Coronilla varia L), cicer milkvetch (Astragrlus cicer L), sericea lespedeza (Lespedeza cuneata (Dum-Cours) G Don) and kura clover (Trifolium ambiguum M Bieb) were subjected to sequential detergent fibre analysis to investigate the effects that the addition of sodium sulphite to neutral detergent has on the recovery and composition of fibre and lignin from forage legumes that vary in levels of proanthocyanidin (PA). Soluble, insoluble and neutral detergent insoluble PA (NDIPA) concentrations were highest in sericea, moderate in crownvetch, sainfoin and birdsfoot trefoil and absent in alfalfa, cicer milkvetch, red clover and kura clover. Addition of sodium sulphite reduced levels of neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), neutral detergent insoluble nitrogen (NDIN) and acid detergent insoluble nitrogen (ADIN) recovered from most forages tested. The addition of sodium sulphite effectively eliminated NDIPA from NDF. The difference between fibre fractions prepared without and with the addition of sodium sulphite during the neutral detergent procedure was related to PA concentration. Neutral detergent fibre difference was positively correlated with soluble PA (r=0.730, p=0.0001), insoluble PA (r=0.905, p=0.0001) and NDIPA (r=0.913, p=0.0001). Acid detergent fibre difference was positively correlated with soluble PA (r =0.796, p =0.0001), insoluble PA (r = 0.976, p = 0.0001) and NDIPA (r = 0.974, p = 0.0001). Acid detergent lignin difference was positively correlated with soluble PA (r=0.846, p=0.0001), insoluble PA (r=0.992, p=0.0001) and NDIPA (r = 0.972, p = 0.0001). Neutral detergent insoluble nitrogen difference was positively correlated with soluble PA (r = 0.475, p = 0.0255), insoluble PA (r =0.579, p = 0.0047) and NDIPA (r =0.570, P =0.0056). Acid detergent insoluble nitrogen difference was positively correlated with soluble PA (r=0.798, p =0.0001), insoluble PA (r = 0.969, P = 0.0001) and NDIPA (r = 0.979, p = 0.0001). Sodium sulphite has large effects on fibre values of PA-containing species. Our results suggest that the difference between fibre fractions prepared with and without the addition of sulphite to neutral detergent may be used to determine the effects of PA on protein solubility in detergents.
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Responses of Lotus corniculatus to environmental change. 2. Effect of elevated CO2, temperature and drought on tissue digestion in relation to condensed tannin and carbohydrate accumulation.
Carter, E.B.; Theodorou, M.K.; Morris, P. 1999. Journal of the Science of Food and Agriculture 79:1431-1440.
Clonal plants of three genotypes of Lotus corniculatus (cv Lee) were grown in eight controlled environments under combinations of two temperature regimes, two CO2 concentrations and two watering regimes. Condensed tannins (proanthocyanidins), in-vitro digestibility, initial rates of gas evolution as an indicator of the initial rates of fermentation of the substrate), volatile fatty acid evolution, and non-structural carbohydrate (NSC) levels were determined in leaves, stems and roots at full flowering. Under control conditions (average midsummer conditions in the United Kingdom) the total condensed tannin content of leaves varied six-fold between genotypes but condensed tannin contents in stems and roots were similar. Condensed tannin levels were significantly increased in leaves and stems of all three genotypes by doubling the CO2 concentration while raising the temperature towards the optimum for growth significantly reduced condensed tannin levels. Drought stress significantly reduced condensed tannin levels in leaves and, particularly, in roots. Nutritive value was inversely related to condensed tannin levels in leaves and a negative relationship was observed between condensed tannin concentrations of more than 25-30 g kg(-1) dry matter and the initial rates of gas evolution when subjected to in-vitro fermentation with rumen micro-organisms. In leaves, digestibility was significantly increased by drought and by increasing temperature but reduced by high CO2. In stems, digestibility was significantly increased by drought, but not significantly affected by increasing temperature, or by high CO2 alone. In roots, digestibility was significantly increased by drought, and decreased by increasing temperature or CO2. Increasing the growth temperature towards optimum growth reduced the content of NSC in all tissues with the greatest changes occurring in root tissue. Doubling the CO2 concentration increased NSC levels in leaves and stems with starch content more than doubled under high CO2 while, in roots, increased levels were only observed in combination with drought stress. There was a linear correlation between condensed tannin concentration and total NSC that was positive for leaves, neutral for stems and negative for roots. The relationship between carbohydrate levels and rates of gas production was negative for leaves and positive for stem and roots.
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Lotus japonicus nodulates and fixes nitrogen with the broad host range Rhizobium sp NGR234.
Hussain, AKMA.; Jiang, Q.Y.; Broughton, W.J.; Gresshoff, P.M. 1999. Plant and Cell Physiology 40:894-899.
Lotus japonicus possesses major advantages as a model legume for the study of plant-microbe interactions. The relative absence of genetic information on its normal microbial partner (i.e., Mesophizobium loti) could limit its utility in research. Here we show for the first time that the broad host range Rhizobium strain NGR234 nodulates and fixes nitrogen in symbiosis with Lotus japonicus ecotypes "Gifu" and "Funakura". We demonstrate that bacterial mutants deficient in nodulation or nitrogen fixation possess the expected phenotype with L. japonicus. Nodulation of L. japonicus was sensitive to nitrate. Vermiculite was an efficient synthetic growth substrate, allowing axenic growth in Magenta jars. The genetic analysis of the Lotus japonicus-Mesorhizobium interaction should be accelerated through the use of this well-defined microsymbiont.
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The final step of pantothenate biosynthesis in higher plants: cloning and characterization of pantothenate synthetase from Lotus japonicus and Oryza sativum (rice).
Genschel, U.; Powell, C.A.; Abell, C.; Smith, A.G. 1999. Biochemical Journal 341:669-678.
We have isolated a Lotus japonicus cDNA for pantothenate (vitamin B-5) synthetase (PS) by functional complementation of an Escherichia coli pan C mutant (AT1371), A rice (Oryza sativum) expressed sequence tag, identified by sequence similarity to PS, was also able to complement the E, coli auxotroph, as was an open reading frame from Saccharomyces cerevisiae (baker's yeast). The Lotus and rice cDNAs encode proteins of approx. 34 kDa, which are 65 % similar at the amino acid level and do not appear to encode N-terminal extensions by comparison with PS sequences from other organisms. Furthermore, analysis of genomic sequence flanking the coding sequence for PS in Lotus suggests the original cDNA is full-length. The Lotus and rice PSs are therefore likely to be cytosolic, Southern analysis of Lotus genomic DNA indicates that there is a single gene for PS. Recombinant PS from Lotus, overexpressed in E, coli AT1371, is a dimer, The enzyme requires D-pantoate, beta-alanine and ATP for activity and has a higher affinity for pantoate (K-m 45 mu M) than for beta-alanine (K-m 990 mu M). Uncompetitive substrate inhibition becomes significant at pantoate concentrations above 1 mM. The enzyme displays optimal activity at about 0.5 mM pantoate (k(cat) 0.63 s(-1)) and at pH 7.8. Neither oxopantoate nor pantoyl-lactone can replace pantoate as substrate. Antibodies raised against recombinant PS detected a band of 34 kDa in Western blots of Lotus proteins from both roots and leaves, The implications of these findings for pantothenate biosynthesis in plants are discussed.
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Proline is involved in water stress responses of Lotus corniculatus nitrogen fixing and nitrate fed plants.
Borsani, O.; Diaz, P.; Monza, J. 1999. Journal of Plant Physiology 155:269-273.
Water stress induced proline accumulation in Lotus corniculatus regardless of the nitrogen source provided to plants, although this accumulation was higher in nitrogen fixing plants. Enzymes related to synthesis and oxidation of proline were analysed. Fd-GOGAT activity and Fd-GOGAT protein content increased in response to water stress in contrast to PDH activity, which decreased under such condition. However, rehydration for 6 h induced an increment in PDH activity. The differential effect of water deficit on enzymes involved in the proline pathway in L. corniculatus plants growing under different nitrogen regimes is discussed. The possible role of nitrate as an osmoprotectant in the place of proline is also considered.
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Genetic nomenclature guidelines for the model legume Lotus japonicus.
Stougaard, J.; Szczyglowski, K.; de Bruijn, F.J.; Parniske, M. 1999. Trends in Plant Science 4:300-301.
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