Search

Melilotus is an important genus of legume plants and an herbage with excellent nitrogen fixation; it can tolerate extreme environmental conditions and possesses important medicinal value. However, there is limited genetic information about the genus; thus, we analysed four chloroplast loci (rbcL, matK, psbA-trnH and trnL-F) and one nuclear region (ITS) to determine the genetic diversity of 199 accessions from 18 Melilotus species. The rbcL and matK sequences were highly conserved, whereas the trnL-F and ITS sequences contained variable and parsimony-informative sites. In our analyses of the single and combined regions, we calculated the pairwise distance, haplotype and nucleotide diversity and gaps and then constructed phylogenetic trees to assess the genetic diversity, and our results revealed significant variations among the different accessions. The genetic distance values were between zero and nine, and based on the combined regions, the highest frequency value was approximately four. Melilotus showed high haplotype and nucleotide diversity, particularly in the ITS sequences, with values of 0.86 and 0.0087, respectively. The single ITS sequence, psbA-trnH, and the combined matK+rbcL+trnL-F (MRT) and matK+rbcL+psbA-trnH+trnL-F+ITS (MRPTI) regions showed interspecific variation in the gap analysis. Phylogenetic trees calculated using ITS, psbA-trnH and MRPTI sequences indicated distinct genetic relationship in 18 species, and these species could be divided into two groups. By determining the genetic diversity of plants, we can evaluate the genetic relationships among species and accessions, providing a basis for preserving and utilizing the genetic resources of Melilotus. [ABSTRACT FROM AUTHOR]

Melilotus, an annual or biennial herb, belongs to the tribe Trifolieae (Leguminosae) and consists of 19 species. As an important green manure crop, diverse Melilotus species have different values as feed and medicine. To identify different Melilotus species, we examined the efficiency of five candidate regions as barcodes, including the internal transcribed spacer (ITS) and two chloroplast loci, rbcL and matK, and two non-coding loci, trnH-psbA and trnL-F. In total, 198 individuals from 98 accessions representing 18 Melilotus species were sequenced for these five potential barcodes. Based on inter-specific divergence, we analysed sequences and confirmed that each candidate barcode was able to identify some of the 18 species. The resolution of a single barcode and its combinations ranged from 33.33% to 88.89%. Analysis of pairwise distances showed that matK+rbcL+trnL-F+trnH-psbA+ITS (MRTPI) had the greatest value and rbcL the least. Barcode gap values and similarity value analyses confirmed these trends. The results indicated that an ITS region, successfully identifying 13 of 18 species, was the most appropriate single barcode and that the combination of all five potential barcodes identified 16 of the 18 species. We conclude that MRTPI is the most effective tool for Melilotus species identification. Taking full advantage of the barcode system, a clear taxonomic relationship can be applied to identify Melilotus species and enhance their practical production. [ABSTRACT FROM AUTHOR]

Melilotus is one of the most important legume plants, in part due to its production of coumarin, but the genetic diversity among the 18 species remains unclear. In the present study, the analysis of genetic diversity of the Melilotus species was performed with simple sequence repeat (SSR) markers. From the PCR amplification, we selected 18 out of 70 primers that were used in previous studies. Three hundred twenty-six sampled individuals were assayed to study the genetic diversity and polymorphisms based on the SSR markers. All analyzed markers were polymorphic, and 287 alleles were identified, with 15.94 alleles per locus detected. The polymorphism information content ( PIC ) values ranged from 0.71 to 0.93, with an average of 0.87, which indicates that the markers were highly informative. Based on the unweighted pair-group method with arithmetic mean (UPGMA) cluster analysis, we found that the 18 species were divided into two clusters. M. italicus and M.​ speciosus from cluster A and M. indicus and M. segetalis from cluster B were closely related. Population structure analysis suggested that the optimum number of groups was three. From the analysis of molecular variance, 17.79% of the variance was due to species differences, 31.61% of the variance was due to differences among populations within species and the remaining 50.60% was due to differences within populations. The results of the present study showed that these SSR markers will benefit the Melilotus research community for genetics and breeding. Furthermore, this study also established the foundation for future breeding programs, genetic improvement and coumarin production in the Melilotus species. [ABSTRACT FROM AUTHOR]

The objective of the present study was to isolate and characterize nodulating bacteria associated with wild legumes. For this purpose, we recovered twenty isolates from root nodules of five wild legume species: Melilotus alles, Melilotus officinalis, Trifolium pratense, Trifolium repens and Medicago sp. Most of the isolates were morphologically analogous with only few exceptions in colony shape, appearance and incubation time. All isolates were Gram negative except T.P2-4. Random amplification of polymorphic DNA showed genetic variation among isolates. The 16S rRNA sequence analysis revealed these isolates as Rhizobium, Sinorhizobium and Paenibacillus. Each of these was also screened for nod D and nod F genes with marked variation at these loci; however, the nucleotide sequence analysis confirmed the presence of nod genes. The assignment of strains to their hosts revealed a unique symbiotic association of Paenibacillus sp. nodulating T .pratense which is being reported here for the first time. [ABSTRACT FROM AUTHOR]

Physiological mechanisms of adaptation to copper-induced stress in two widespread legume plants, white sweet clover ( Melilotus albus Merik.) and zigzag clover ( Trifolium medium L.), growing in habitats differing in the man-made pollution. An antioxidant plant defense system was activated in response to 10 mM CuSO, which is a stress factor. Specific biochemical features related to adaptation to soil contamination with copper were observed in tested plant species. Superoxide dismutase was activated in response to stress in both species from various habitats. M. albus from the impact zone manifested the better capacity of proline accumulation as compared with plants from less polluted habitats. T. medium plants from the impact zone contained more active peroxidase. It was suggested that plants growing for a long time under stressful conditions manifest the greater tolerance to copper ions than plants, which did not experience stress or were subjected to the milder stress. [ABSTRACT FROM AUTHOR]

Abstract: Annual pasture legumes with high tolerance of combined salinity and waterlogging are needed for saline areas in many rain-fed agricultural regions. Melilotus siculus is an annual legume from saline marshy areas of the Mediterranean with potential use in saline pastures and, based on descriptions of its native habitat, was hypothesised to tolerate combined salinity and waterlogging. Experiments compared M. siculus to Trifolium michelianum and Medicago polymorpha, other annual pasture legumes with reported salt or waterlogging tolerances, with 0–450mM NaCl in hydroponics or in sand culture. Tolerance to combined salinity and waterlogging was also evaluated at 150, 400 and 550mM NaCl in a stagnant deoxygenated nutrient solution. M. siculus was substantially more salt tolerant than the other two species. At 450mM NaCl, shoot DM of M. siculus was 30% of control, compared with only 15% for the other species. M. siculus was also the most tolerant species to combined salinity and stagnant treatment, and produced new leaves even after 14d in stagnant nutrient solution with 550mM NaCl (∼ sea water salinity). In comparison, T. michelianum and M. polymorpha only survived up to 5d in stagnant solution with 400mM NaCl. Even at only 150mM NaCl in stagnant solution, shoot DM was just 30% of control for T. michelianum and M. polymorpha, compared to 60% for M. siculus. Tolerance to combined salinity and waterlogging was associated with higher root porosity and regulation of shoot Na+ and Cl−, with the more tolerant M. siculus having similar shoot Na+ and Cl− concentrations for both aerated-saline and stagnant-saline treatments. In summary, M. siculus is a pasture legume that can grow at high salinity (up to 550mM) even when in combination with waterlogging, as root porosity and associated O2 transport presumably enables continued regulation by the roots of Na+ and Cl− entry under these dual stress conditions. [Copyright &y& Elsevier]

Melilotus officinalis, an annual or biennial dicot species of the family Fabaceae, is a common herb that is often found in disturbed habitats and agricultural areas in many parts of the temperate and tropical regions of the world. It is a native of Mediterranean area through central Eurasia east to Tibet. M. officinalis is considered to be an aggressive, highly invasive species, noxious and "cosmopolitan" weed in native prairie community, meadows and several crops of major importance, such as wheat, soybean, onion, olive trees and strawberry. It is adapted to a wide range of climatic conditions and grows on a wide variety of soil types. As opportunistic biennial, M. officinalis possesses characteristics that make it competitive in nature and alter soil characteristics. It colonizes disturbed areas, produces a large number of seeds, grows early in the season to create a tall dense colony, producee extensive root systems and fixes nitrogen for its immediate use. The management of M. officinalis can be achieved by herbicide application, mechanical (hand pulling, mowing, grazing), physical (fire) and biological control methods. The plant is reported to be honey plant as well as for forage and for green manure, edible and is also used for medicinal purposes. [ABSTRACT FROM AUTHOR]

Three new triterpene oleanane glycosides, melilotosides A, B, and C, and non-glycosylated soyasapogenol B were isolated from Melilotus officinalis (L.) Pall. (Fabaceae) roots. The structures of the glycosides were proved using chemical transformations and spectral data. Melilotoside A is soyasapogenol B 3-O-β-Dxylopyranoside; melilotoside B, soyasapogenol B 3-O-[β-D-galactopyranosyl-(1-2)-f-D-xylopyranoside]; melilotoside C, soyasapogenol B 3-O-[α-L-rhamnopyranosyl-(1-2)-β-D-galactopyranosyl(1-2)-β-Dxylopyranoside]. [ABSTRACT FROM AUTHOR]

Abstract: Previously unexploited legume species may offer utilization potential where environmental stresses constrain the use of more conventional forage crops. Melilotus indicus (L.) All., Yellow sweet clover, occurs as a weed in different habitats in Egypt. It grows in moderately saline areas, where traditional forage legumes cannot be cultivated. Our extensive field studies have recorded the species in many different habitats ranging from healthy agricultural lands to abandoned saline areas. The studied plants maintained high nodulation capacity (68 – 95%) and nitrogenase activities (about 1.81μmolC2H4 plant−1 h−1) in different habitats. Greenhouse experiments demonstrated that seed germination was maintained at 80% when growing on substrats containing 200mM NaCl and that 25% of the germination capability was preserved when 300mM NaCl was added to the growth medium. The growth rate of seedlings was not significantly affected by 200mM NaCl but was reduced by 30% under 300mM NaCl. It is supposed that M. indicus uses a salt inclusion mechanism for maintaining growth under saline conditions, as it accumulated high amounts of Na+ and Cl− ions. Leaf succulence and indices of leaf water status did not differ among the salt treatments, whereas relative water content was reduced by only 3% and water content at saturation increased by about 14% at high salt concentrations in the growing medium. Our results suggest recommending the cultivation of M. indicus in salt-affected soils, which are widespread and pose a problem for the farmers of Egypt and other countries in the world''s arid belt. [Copyright &y& Elsevier]

Abstract: Ensifer meliloti (formerly Sinorhizobium meliloti) was first considered as a specific microsymbiont of Medicago, Melilotus and Trigonella. However, strains of E. meliloti were recovered from root nodules of various legume species and their symbiotic status still remains unclear. Here, we further investigate the specificity of these strains. A collection of 47 E. meliloti strains isolated in Tunisia from root nodules of Medicago truncatula, Medicago sativa, Medicago ciliaris, Medicago laciniata, Medicago marina, Medicago scutellata, Phaseolus vulgaris, Cicer arietinum, Argyrolobium uniflorum, Lotus creticus, Lotus roudairei, Ononis natrix, Retama raetam, Genista saharae, Acacia tortilis, Hedysarum carnosum and Hippocrepis bicontorta were examined by REP-PCR fingerprinting, PCR-RFLPs of the 16S-23S rDNA IGS, the nifH gene and nifD-K intergenic spacer, and sequencing of 16S rRNA and nodA genes. Their nodulation range was also assessed by cross-inoculation experiments. No clear correlation was found between chromosomal backgrounds and host plants of origin. The nodulation polyvalence of the species E. meliloti was associated with a high symbiotic heterogeneity. On the basis of PCR-RFLP data from the nifH gene and nifD-K intergenic spacer, E. meliloti strains isolated from non-Medicago legumes harboured distinct genes and possessed wider host ranges. Some strains did not nodulate Medicago species. On the basis of nodA phylogeny, the majority of the Tunisian strains, including strains from Medicago, harboured distinct nodA alleles more related to those found in E. medicae than those found in E. meliloti. However, more work is still needed to characterize this group further. The diversity observed among M. laciniata isolates, which was supported by nodA phylogeny, nifH typing and the efficiency profile on M. ciliaris, indicated that what was thought to be bv. medicaginis is certainly heterogeneous. [Copyright &y& Elsevier]

In the montane grasslands of Rocky Mountain National Park, Colorado, non-native plant species are affecting the distribution and cover of native plant species. Two exotic nitrogen-fixing Eurasian sweetclover species (Melilotus officinalis and M. alba) occur in patches that have less available nitrogen (N) and a species composition different from surrounding grassland patches. I tested whether burning sweetclover-invaded patches would increase native grass and perennial diversity and available soil nitrogen at this elevation. I burned 24 sweetclover-invaded and noninvaded field plots with a propane torch in May 1999. Burning increased species richness and ground cover. Specifically, one year later native, grass, and perennial species increased in previously invaded patches and sweetclover or other exotic species associated with sweetclover did not increase. Soil ammonium (NH4+) levels increased immediately after the burn in May, and nitrate (NO3-) levels increased later in July and August. New species appeared only in burned plots. While other methods to reduce sweetclover might remove resources, fire increases light, space, and nutrient availability for native species that, in turn, suppress the exotic species. [ABSTRACT FROM AUTHOR]

Four different low molecular weight (LMW) RNA profiles, designated I–IV, among 179 isolates from Medicago, Melilotus and Trigonella species growing in a field site in Northern Spain were identified. From sequence analysis of the 16S rRNA, atpD and recA genes as well as DNA–DNA hybridization analysis with representatives of each LMW RNA profile it was evident that isolates with LMW RNA profiles I and II belonged to Sinorhizobium meliloti and those displaying profiles III and IV to Sinorhizobium medicae. Therefore, two distinct LMW RNA electrophoretic mobility profiles were found within each of these two species. Collectively, LMW RNA profiles I and II (identified as S. meliloti) were predominant in Melilotus alba, Melilotus officinalis and Medicago sativa. Profiles III and IV (identified as S. medicae) were predominant in Melilotus parviflora, Medicago sphaerocarpa, Medicago lupulina and Trigonella foenum-graecum. All the four LMW RNA profiles were identified among isolates from Trigonella monspelliaca nodules. These results revealed a different specificity by the hosts of the alfalfa cross-inoculation group towards the two bacterial species found in this study. [ABSTRACT FROM AUTHOR]

Critical soil-test boron (B) levels and consequent fertilizer recommendations for lentils have been traditionally based on values (0.5 µg/g) developed for alfalfa, sweet clover, and other legumes commonly grown in the inland Pacific Northwest. The purpose of this study was to define the relationship between soil-test B values and lentil yields. Fifty-nine field studies using B were conducted between 1980 and 2003 on Mollisols and Alfisols in northern Idaho and eastern Washington. Based on the results of these studies, the critical soil B value for optimum lentil yields is 0.4 µg/g. These studies found that the traditionally used critical soil-test B values were higher (0.5 µg/g) than needed to achieve optimum yield. Even though this newly established critical B value is lower, about 50% of the soils in the region are too low in B to produce optimum lentil yields. [ABSTRACT FROM AUTHOR]

Melilotus indica All. [Chopra, R.N., Nayar, S.L. and Chopra, I.C. (1956) Glossary Indian Med. Plants , 164 C.S.I.R. Publication New-Delhi; Kirtikar, K.R. and Basu, B.D. (1935) Indian Medicinal Plants , 2nd Ed., Vol. I , pp. 703–704 Lalit Mohan Basuan Co. Allahabad. The Wealth of India (1962) A Dictionary of Raw Materials and Industrial Products , Vol. VI , pp. 329–331 (C.S.I.R. Publication: New-Delhi)] belongs to family Leguminosae, which is commonly known as ‘Banmethi’ in Hindi. It is found in North India, extending into S. Persia, S. Europe and the Tropical zone of India. The seeds are used as an anthelmintic, an antipyretic, for curing heart diseases, bronchitis, leprosy, bowel complaints and infantile diarrhea. The plant has also been used as a discutient, emollient, and as a fomentation. It is also useful in a plaster for swelling. It is considered astringent and narcotic. Earlier workers have reported the presence of C-glycosides [Sayed, E.L., Ishak, M.S. and Mabry, T.J. (1997) Asian J. Chem. , 9 , 551], methylene-dioxypterocarpan (MIS6) [Saxena, V.K. and Nigam, S. (1997) Fitoterapia , 68 , 343–345], pterocarpane (MIS2) [Saxena, V.K. and Nigam, S. (1996) J. Institution Chem. 68 , 122–125] and prenylated pterocarpan [Saxena, V.K. and Nigam, S. (1997) Fitoterapia , 68 , 403–407] from this plant. Here, we report the isolation of the new flavone glycoside 5,7,4'-trihydroxy-6,3'-dimethoxyflavone-7- O -a-l-arabinopyranosyl(1?6)- O -ß-d-galactopyranoside ( 1 ) from the seeds of this plant. [ABSTRACT FROM AUTHOR]

Respiration in support of N2 fixation by rhizobia in legume root nodules depends on an adequate supply of O2, but excessive O2 can damage nitrogenase, the key enzyme. The movement of O2 into and within the nodule is driven by gradients in the concentration of O2 or in the oxygenation of the O2‐carrier, leghaemoglobin. Steeper gradients may increase flux to the sites of respiration, but gradients also raise the possibility of inadequate O2 in some nodule zones and excessive O2 in others. No detailed study of O2 gradients in the interior of nodules has been published previously. Spectral changes in leghaemoglobin with oxygenation, previously used to measure the average O2 status of the nodule interior, were used to map longitudinal gradients in O2 and in respiratory capacity in the elongated nodules of alfalfa (Medicago sativa L.) and sweetclover (Melilotus officinalis L.). Variability among nodules under air in the magnitude and direction of internal O2 gradients was seen in both species. Despite consistently higher respiratory capacity near the meristematic tip, a majority of nodules had higher O2 towards the tip than towards the base. These results contrast with a previous report, apparently based on limited data, but they are consistent with anatomical and tracer studies showing higher gas permeability near the tip. [ABSTRACT FROM PUBLISHER]

The allocation of biomass and mineral elements Na, K, Ca, P, N, Fe, Cu, Mn and Zn) during the ontogenetic cycle of annual sweetclover (Melilotus segetalis (Brot.) Ser.) growing under favourable and saline conditions has been studied. Plants were grown in a glasshouse, in pots with siliceous substrate- and watered with Hoagland solution. Half were salinized by adding 170 mol m-3 NaCl (15 dS m-1 to the solution. Eleven harvests at 15 d intervals measured the dry weight distribution within the plant and the mineral composition. Allocation relative to biomass (ARB) in each plant organ, both under favourable and salt-stress conditions, was calculated For each mineral element. Biomass and mineral elements were allocated independently within M. segetalis and the general pattern changed with age and was affected by salinity. Salt-stressed plants were smaller and invested proportionately more biomass in leaves. Na was accumulated in roots of young plants and excluded from leaves and fruits, whereas K was depleted from roots and accumulated in leaves and fruits. immobile Ca accumulated in leaves; with age. Phloem-mobile P and N were translocated to flowers and fruits. Fe, Cu and Zn were diluted in leaves and not affected by salt, whereas Mn concentration increased with age and salinity. The switch to reproduction and increased demand fur nutrients induced drastic changes in the allocation pattern of mineral elements. Salinity induced a re-allocation of biomass and mineral elements in all plant organs except the reproductive structures, as part of a whole-plant response to minimize salt toxic effects, to achieve osmotic adjustment, to present the reproductive output, and to compensate nutrient imbalance. [ABSTRACT FROM AUTHOR]

The aim of this work was to examine variation for activity of symbiosis with Rhizobium meliloti in alfalfa, sweet clover and fenugreek. Seed specimens were obtained from the collection of the All-Union Research Institute for Plant Breeding and Rhizobium strains from the All-Union Research Institute for Agricultural Microbiology, both in Leningrad. Sterile methods of vegetative culture were employed. Statistical analysis of data on inter- and intracultivar variation allow one to suppose that in alfalfa and sweet clover, nitrogenase activity and symbiotic efficiency (ability of plants to increase biomass after inoculation) are controlled by different groups of genes. The latter symbiotic property is more strictly controlled by host genotype than the former. Fenugreek appeared to be more variable in its capacity for symbiosis than alfalfa and sweet clover. Differences between genotypes in symbiotic activity correlate with division into subspecies and are inherited in self-fertile progeny of fenugreek plants. Differences between R. meliloti strains for the efficiency of symbiosis with heterogenic natural fenugreek population are expressed to a lesser degree than with plants of more homogenic cultivar populations. [ABSTRACT FROM AUTHOR]

We describe specific primers that amplify nine microsatellite DNA loci from Melilotus alba and Melilotus officinalis, both invasive plant species (Fabaceae) throughout North America. Allelic diversity was slightly lower for M. alba than for M. officinalis, as was expected heterozygosity. For both species, heterozygote deficit was observed at several loci. Genotypic diversity was very high for both species; the 29 plant samples of each species all had different multilocus genotypes. These markers will be used to determine the origins of the sweetclover invasion in Alaska and to compare patterns of diversity between subarctic and lower latitude populations. [ABSTRACT FROM AUTHOR]

The article focuses on the High Performance Liquid Chromatography (HPLC) and analysis of Phenolic compounds in yellow sweet clover. Yellow sweet-clover (YSC) is a biennial or perennial grassy plant of Fabaceae family, which widely occurs in the European part of Russia. This study was aimed at an HPLC analysis of the complex of phenolic compounds contained in YSC leaves. The experiments were performed with air-dry material prepared from YSC species collected in the period of blooming in the Kursk region. The analyses were performed on a Gilson Model 305 liquid chromatograph. The chromatograms of the samples prepared from YSC grass revealed 18 phenolic compounds, predominantly representing coumarins, flavonoids, and derivatives of phenolocarboxylic acids.

Sinorhizobium meliloti participates in a nitrogen-fixing symbiosis with legume plant host species of the genera Medicago, Melilotus, and Trigonella. We recently identified an S. meliloti two-component sensory histidine kinase, CbrA, which is absolutely required to establish a successful symbiosis with Medicago sativa (K. E. Gibson, G. R. Campbell, J. Lloret, and G. C. Walker, J. Bacteriol. 188:4508-4521, 2006). In addition to having a symbiotic defect, the cbrA::Tn5 mutant also has free-living phenotypes that suggest a cell envelope perturbation. Because the bases for these phenotypes are not well understood, we undertook an identification of CbrA-regulated genes. We performed a microarray analysis and compared the transcriptome of the cbrA::Tn5 mutant to that of the wild type. Our global analysis of gene expression identified 162 genes that are differentially expressed in the cbrA::Tn5 mutant, including those encoding proteins involved in motility and chemotaxis, metabolism, and cell envelope function. With regard to those genes with a known role in symbiosis, we observed increased expression of nine genes with overlapping functions in bacterial invasion of its host, which suggests that the mutant could be competent for invasion. Since these CbrA-repressed genes are vital to the invasion process, it appears that down-regulation of CbrA activity is important at this stage of nodule development. In contrast, our previous work showed that CbrA is required for bacteria to establish themselves within the host as nitrogen-fixing symbionts. Therefore, we propose a model in which CbrA functions as a developmental switch during symbiosis. [ABSTRACT FROM AUTHOR]