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Identifying sustainable resources of natural fibers is essential due to their high demand in industrial applications such as automotive and biomedical materials. Two alternative fibers obtained from canola and sweet clover stalks were characterized for their properties using energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), contact angle, and tensile test. Hemp and flax fibers, both in use as industrial fibers, were also characterized as conventional fibers. Results showed that all the fibers had the same chemical elements (carbon, oxygen, magnesium, and potassium) and chemical bonds. The crystallinity index for the alternative fibers ranged from 62 to 71%, which was close but lower than the conventional fibers (82% for hemp and 80% for flax). The thermal stability of the alternative fibers was around 220 °C, close to the conventional fibers (230 °C). The alternative fibers had contact angles of less than 90°, showing high surface energy. Since the alternative fibers had a low Young's modulus and tensile strength (5.57–8.52 GPa and 57.45–71.26 MPa, respectively), they are suitable for some specific applications in the biomedical industry. In contrast, conventional fibers are suitable where a higher stiffness and strength is required. [ABSTRACT FROM AUTHOR]

White sweet clover (Melilotus albus) cultivation, despite its many positive features such as the high yield of green mass, as well as protein content, is currently not widespread. This study aimed to determine the effect of the different sowing densities (500, 1000, and 1500 seeds per m2) and harvesting at different growth stages (before budding, budding, and full flowering) on the quality of fodder from the white sweet clover (Adela variety). The field experiment was carried out in the years 2018–2020 in a split-plot design. Plant biometric measurements, green and dry yield, the content of total protein, crude fat, crude fiber, ash, macro and microelements, and coumarin content were determined. The results show that an increase in the sowing density significantly increased the plant population after emergence and green and dry matter. However, it does not affect the total protein, crude fat, crude fiber, ash, macro and microelements, and coumarin content. Harvesting plants at the flowering stage increased plant height and green fodder yield. Plants harvested at the prebudding phase were characterized by the highest share of leaves (40.3%) and were the most abundant in protein (21.7%) and minerals (ash content 12.71%). Unfortunately, sweet clover at this growth stage contained the highest level of coumarin, which limits its use in animal feed. [ABSTRACT FROM AUTHOR]

Summary: Melilotus species are used as green manure and rotation crops worldwide and contain abundant pharmacologically active coumarins. However, there is a paucity of information on its genome and coumarin production and function. Here, we reported a chromosome‐scale assembly of Melilotus albus genome with 1.04 Gb in eight chromosomes, containing 71.42% repetitive elements. Long terminal repeat retrotransposon bursts coincided with declining of population sizes during the Quaternary glaciation. Resequencing of 94 accessions enabled insights into genetic diversity, population structure, and introgression. Melilotus officinalis had relatively larger genetic diversity than that of M. albus. The introgression existed between M. officinalis group and M. albus group, and gene flows was from M. albus to M. officinalis. Selection sweep analysis identified candidate genes associated with flower colour and coumarin biosynthesis. Combining genomics, BSA, transcriptomics, metabolomics, and biochemistry, we identified a β‐glucosidase (BGLU) gene cluster contributing to coumarin biosynthesis. MaBGLU1 function was verified by overexpression in M. albus, heterologous expression in Escherichia coli, and substrate feeding, revealing its role in scopoletin (coumarin derivative) production and showing that nonsynonymous variation drives BGLU enzyme activity divergence in Melilotus. Our work will accelerate the understanding of biologically active coumarins and their biosynthetic pathways, and contribute to genomics‐enabled Melilotus breeding. [ABSTRACT FROM AUTHOR]

Copyright of Agronomy Science is the property of University of Life Sciences in Lublin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Coumarin is a plant secondary metabolite responsible for the health-promoting properties of the Melilotus officinalis herb used in traditional medicine in the treatment of lymphedema and chronic venous diseases. The aim of this study was to analyze the possibility of honey enrichment with coumarin derived from sweet clover (Melilotus) in two different ways: herb honey and herb-infused honey production. Herb honey was obtained by feeding bees with sugar syrup enriched with a M. officinalis herb water infusion, whereas herbal macerates in multifloral honey were prepared with crushed flowers (fresh and dried) of M. officinalis and Melilotus albus at 20 °C in dark place for 6 months. Melilotus albus nectar honey (n = 14) was used as control. Using HPLC analysis, the highest content of coumarin (from 41.33 to 137.89 mg/kg) and its precursor o-coumaric acid (from 6.57 to 25.15 mg/kg) in M. officinalis flowers-infused honey were found. Herb honey contains 4.48 mg/kg coumarin and for the first time, this compound was determined in nectar honey from Polish M. albus honey (0.05 to 0.88 mg/kg). The addition of Melilotus flowers enhanced antioxidant activity (measured by FRAP, DPPH and PCL methods) of infused-honey in comparison to multifloral honey (control) and herb honey. The coumarin and o-coumaric acid were weakly correlated with antioxidant activity. It was found that only herb-infused honey can be proposed as the natural safe remedy for venous diseases prevention. [ABSTRACT FROM AUTHOR]

Background and Aims Submergence is a severe stress for most plants. Melilotus siculus is a waterlogging- (i.e. root zone hypoxia) tolerant annual forage legume, but data were lacking for the effects of partial and full submergence of the shoots. The aim was to compare the tolerance to partial and full submergence of 15 M. siculus accessions and to assess variation in traits possibly contributing to tolerance. Recovery ability post-submergence was also evaluated. Methods A factorial experiment imposed treatments of water level [aerated root zone with shoots in air as controls, stagnant root zone with shoots in air, stagnant root zone with partial (75 %) or full shoot submergence] on 15 accessions, for 7 d on 4-week-old plants in a 20/15 °C day/night phytotron. Measurements included: shoot and root growth, hyponastic petiole responses, petiole gas-filled spaces, leaflet sugars, leaflet surface hydrophobicity, leaflet gas film thickness and phellem area near the base of the main root. Recovery following full submergence was also assessed. Key Results Accessions differed in shoot and root growth during partial and full shoot submergence. Traits differing among accessions and associated with tolerance were leaflet gas film thickness upon submergence, gas-filled spaces in petioles and phellem tissue area near the base of the main root. All accessions were able to re-orientate petioles towards the vertical under both partial and full submergence. Petiole extension rates were maintained during partial submergence, but decreased during full submergence. Leaflet sugars accumulated during partial submergence, but were depleted during full submergence. Growth resumption after full submergence differed among accessions and was positively correlated with the number of green leaves retained at desubmergence. Conclusions Melilotus siculus is able to tolerate partial and full submergence of at least 7 d. Leaflet surface hydrophobicity and associated gas film retention, petiole gas-filled porosity and root phellem abundance are important traits contributing to tolerance. Post-submergence recovery growth differs among accessions. The ability to retain green leaves is essential to succeed during recovery. [ABSTRACT FROM AUTHOR]

Abstract Invasive species control requires understanding the mechanisms behind their establishment and their interactions with other species. One potential ecosystem alteration influencing the establishment and spread of invasive species is anthropogenic nitrogen enrichment, from sources like introduced or invasive nitrogen (N)-fixing legumes, which can alter competition between native, non-native, and invasive plants. Kentucky bluegrass (Poa pratensis) and N-fixing yellow sweet clover (Melilotus officinalis) are exotic to the Great Plains and are currently invading and degrading native rangelands by altering ecosystem processes and displacing native plants. Therefore, we investigated how N enrichment from yellow sweet clover affects the aboveground biomass production of Kentucky bluegrass and western wheatgrass (Pascopyrum smithii), a native cool-season grass, the ranges of which overlap in the northern Great Plains. In a controlled greenhouse environment, we conditioned experimental pots by growing yellow sweet clover and terminating each plant after 8 wk. Conditioned soils contained ≈ 340% more plant-available N than untreated soils 2 wk after yellow sweet clover death. We then grew Kentucky bluegrass and western wheatgrass transplant seedlings in interspecific and intraspecific pairs in pots conditioned either with or without yellow sweet clover for 12 wk. Aboveground biomass production of both Kentucky bluegrass and western wheatgrass grown in interspecific and intraspecific pairs increased in conditioned soils. However, when grown together in conditioned pots, the increase in Kentucky bluegrass biomass relative to untreated pots (520%) was double that of the increase in western wheatgrass biomass (260%). Our results reveal that Kentucky bluegrass can use increased soil N to produce proportionally more aboveground biomass than western wheatgrass, a native grass competitor. Thus, our results suggest yellow sweet clover and other sources of N enrichment may facilitate the invasion of Kentucky bluegrass. [ABSTRACT FROM AUTHOR]

To improve the serious situation of soil degradation in China, tests were carried out to study the improvement effects of Russian Melilotus officinalis on the low base saturation acid soil, the alkaline-saline soil and the heavy metal contaminated soil. The results showed that M. officinalis could improve the low base saturation acid soil, increase the salt, alkali content, mineral nutrition and organic nutrient, which indicated that M. officinalis could be planted in the acid soil, and had a significant ecological eefect on soil improvement. M. officinalis achieved a remarkable eefect on improving the alkaline-saline soil (pH 8.5 - 9.5) that the soil desalted, dealkalized and had more organic nutrient. Moreover, M. ofifcinalis could improve the heavy metal contaminated soil and had the ability to enrich and transform heavy metal elements, especially Cd and Ni, thereby presenting significant repair eefects on soil improvement. Therefore, Russian M. ofifcinalis had multiple--fects on degraded soil improvement, so it is worthy of application and popularization. [ABSTRACT FROM AUTHOR]

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]

Background and Aims Soil waterlogging adversely impacts most plants. Melilotus siculus is a waterloggingtolerant annual forage legume, but data were lacking for the effects of root-zone hypoxia on nodulated plants reliant on N2 fixation. The aim was to compare the waterlogging tolerance and physiology of M. siculus reliant on N2 fixation or with access to NO3-. Methods A factorial experiment imposed treatments of water level (drained or waterlogged), rhizobia (nil or inoculated) and mineral N supply (nil or 11 mm NO3-) for 21 d on plants in pots of vermiculite in a glasshouse. Nodulation, shoot and root growth and tissue N were determined. Porosity (gas volume per unit tissue volume) and respiration rates of root tissues and nodules, and O2 microelectrode profiling across nodules, were measured in a second experiment. Key Results Plants inoculated with the appropriate rhizobia, Ensifer (syn. Sinorhizobium) medicae, formed nodules. Nodulated plants grew as well as plants fed NO3-, both in drained and waterlogged conditions. The growth and total N content of nodulated plants (without any NO3- supplied) indicated N2 fixation. Respiration rates (mass basis) were highest in nodules and root tips and lowest in basal root tissues. Secondary aerenchyma (phellem) formed along basal root parts and a thin layer of this porous tissue also covered nodules, which together enhanced gas-phase diffusion of O2 to the nodules; O2 was below detection within the infected zone of the nodule interior. Conclusions Melilotus siculus reliant on N2 fixation grew well both in drained and waterlogged conditions, and had similar tissue N concentrations. In waterlogged conditions the relatively high respiration rates of nodules must rely on O2 movement via the aerenchymatous phellem in hypocotyl, roots and the outer tissue layers of nodules. [ABSTRACT FROM AUTHOR]

This paper explores the salt-tolerance response ofMelilotusspecies, a forage legume, based on tolerance/susceptibility indices, leaf water relations, leaf/root ion concentrations and multivariate (factor and function discriminate) analyses. In a greenhouse experiment, salinity-susceptibility of 12 accessions ofMelilotus(M. albus, M. indicus, M. officinalis) in addition, two controls (alfalfa and Persian clover) were evaluated at 0 mM, 100 mM, 200 mM, and 300 mM of sodium chloride (NaCl). The experiment was conducted in a split plot design with two replications. Stress tolerance score (STS) was calculated based on tolerance/susceptibility indices. Salt-tolerant accessions were identified. An extracted bi-plot based on factor analysis confirmed the results of tolerance/susceptibility indices. There were significant correlations between STS and multivariate statistics. Root potassium cation (K+) concentration was higher inMelilotusspecies than the control species in all the salinity treatments. STS, root K+concentration, leaf turgidity, and leaf succulence characteristics can be used for screening salinity-tolerance inMelilotusaccessions. In all treatments,M. officinalis, M. indicus, andM. albuswere salinity-tolerant species in descending order. Abbreviations: Total biomass yield under control (Yp) and stress (Ys) mediums, geometric mean productivity (GMP), leaf area (LA), leaf tissue density (LTD), linear regression coefficient (b), mean productivity (MP), relative water content (RWC%), Succulence (S), specific leaf area (SLA), stress susceptibility index (SSI), stress tolerance index (STI), tolerance (TOL), water content at saturation (WCS), water saturation deficit (WSD), sodium chloride (NaCl), potassium cation (K+), sodium cation (Na+), analysis of variance (ANOVA), least significant difference (LSD), alfalfa control accession (CHA), Persian clover control accession (CHC), coefficient of variation (CV), statistics of factor (F) and discriminate function (D) [ABSTRACT FROM AUTHOR]

Melilotus albus Medik. is a legume species with potential to be used as a forage or conserved fodder in Northwest China. Breeding M. albus as a forage crop is focused on simultaneously improving forage yield and reducing coumarin (Cou) content. The goal of the present study was to estimate genotypic variation for several key agronomic traits and to evaluate the impact of single-trait selection and Smith--Hazel-index-based multitrait selection for herbage dry weight (DW), plant height (PH), stem number (SN), and leaf area (LA). A quantitative genetic analysis was conducted on trait measurements from 25 half-sib (HS) families evaluated at Yuzhong and Linze, in China. Significant (P < 0.05) genotypic variation among the HS families for all traits was observed. There was also significant (P < 0.05) genotype x environment interaction for all traits except for LA. The predicted genetic gain, based on estimated genotypic variance, for single-trait selection varied from 2.3 to 30.3% per selection cycle. Pattern analysis of the HS family ´ multitrait best linear unbiased prediction matrix provided a graphical summary of the association among the traits, as well as the four HS family groups generated from clustering. Some members within Group 1 could be crossed to generate a breeding population to be used in recurrent selection for M. albus cultivar development in Northwest China. The applicability of a Smith--Hazel selection index to increase expression of the traits DW, PH, and SN and reduce LA, indirectly reducing Cou content, was confirmed. This index enabled identification of families for increasing key biomass traits and decreasing Cou production. [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]

Most of Melilotus Miller species, a forage legume, contain coumarin, an unfavorable component in their shoot. There is no information concerning coumarin on Iranian Melilotus germplasms. It is crucial for plant breeders to know the concentration of this component in the breeding materials, its relationship with other traits and with genotype geographic origin. In a two-year field study a total of 196 accessions of biennial Melilotus were planted in two replications in March 2014. Thirty-nine agro-morphobiochemical traits were recorded according to standard descriptors. Fluorescencemetery assay was applied to detect free, conjugated, and total coumarin concentrations in plant leaves. The data were subjected to correlation, path, regression, factor, and cluster analyses. Total coumarin concentration varied from 0.09 to 5.27% of leaf dry weight (LDW) with a mean of 1.63 ± 0.08% of LDW among accessions. In M. officinalis, correlation analysis showed no significant correlation between coumarin concentration and cotyledon, hypocotyl, and stem colors. Therefore, no early predicting trait was determined to estimate coumarin concentration in the early growth phases of the germplasms. A positive linear relationship between leaf area and total coumarin concentration was observed by path and regression analyses. Based on factor analysis and extracted bi-plot, the scatter of accessions with low coumarin and high forage yield was determined. Materials were divided into three groups by k-means cluster analysis. There was no clear pattern between coumarin concentration and genotype geographic origin. The findings could be utilized by Melilotus breeders to apply in their breeding programs. [ABSTRACT FROM AUTHOR]

Allodynia is a main symptom of the peripheral neuropathy induced by vincristine treatment. Theoesberiven F, a combination of Melilotus extract and proxyphylline, is currently used for the treatment of inflammatory conditions due to its potent anti-inflammatory and analgesic properties. The anti-allodynic effect of theoesberiven F on mechanical and cold allodynia in a rat model of vincristine-induced neuropathy was investigated in the present study. Intraperitoneal vincristine injections were administered to male Sprague-Dawley rats at a dose of 0.1 mg/kg/day over 12 days (5 days of injection, a 2-day cessation and 5 days of injection). Rats that were allodynic following the vincristine injections were randomly allocated into four groups. Normal saline was injected into rats in the control group. Theoesberiven F (0.1, 0.25 and 0.5 mg/kg) was administered to rats in the three experimental groups, respectively. Mechanical and cold allodynia were measured at preadministration and at 15, 30, 60, 90, 120, 150 and 180 min following the intraperitoneal administration of normal saline or theoesberiven F. The decreased paw withdrawal threshold induced by vincristine injection was increased by theoesberiven F administration. The increased withdrawal frequency to cold stimuli developed by vincristine was reduced by theoesberiven F administration. The results of this study suggest that the administration of theoesberiven F may be beneficial in reducing the mechanical and cold allodynia developed during vincristine treatment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Melilotus comprises 19 species, while the phylogenetic relationships between species remain unclear. In the present work, three chloroplast genes, rbcL, matK, trnL-F, and one nuclear region, ITS (internal transcribed spacer) belonging to 48 populations of 18 species of Melilotus were sequenced and phylogenetic trees were constructed to study their interspecific relationships. Based on the phylogenetic tree generated in this study using rbcL analysis, the Melilotus genus is clearly monophyletic in the legume family. Both Bayesian and maximum-parsimony approaches were used to analyze the data. The nrDNA ITS provided more informative characteristics (9.8%) than cpDNA (3.0%). Melilotus contains two closely related groups, clade I and clade II. M. spicatus, M. indicus and M. segetalis have a close relationship. M. infestus, M. siculus and M. sulcatus are closely related. The comparing between molecular phylogeny and flower color classification in Melilotus showed that the flower color is not much informative for phylogenetics of this genus. [ABSTRACT FROM AUTHOR]

We describe and figure the previously unknown male of Hypanthidioides (Ctenanthidium) bifasciata (Urban, 1993) based on specimens reared from a trap nest along with a female. This species, originally known only from the type specimen collected in Colonia, Uruguay, is also newly recorded from Buenos Aires, Argentina. We provide for the first time information on the nest structure and, based on the analysis of pollen grains from brood cells, record five host plant species belonging to the families Apiaceae, Asteraceae, Brassicaceae, and Fabaceae. Most pollen grains belong to an undetermined species of the genus Melilotus L. (Fabaceae). [ABSTRACT FROM AUTHOR]

As a Traditional Chinese Medicine, Melilotus extracts have been reported to function as an anti-inflammatory agent, antioxidant and inhibitor of capillary permeability. The present study aimed to identify the mechanisms by which Melilotus interferes with inflammation-associated and oxidative stress pathways during sepsis. An animal model of cecal ligation-perforation (CLP)-induced sepsis was established. Two hours prior to surgery, animals in the treatment group were administered 25 mg/kg Melilotus extract tablets and subsequently every 8 h. At 24 h post-administration, pathological modifications in lung tissue and expression levels of tumor necrosis factor-α-induced protein-8-like 2 (TIPE2) expression, nuclear factor (NF)-κB, toll-like receptor 4 (TLR4), heme oxygenase-1 (HO-1), inhibitor of κB kinase (IκB), pro-inflammatory mediators (interleukin-6 and tumor necrosis factor-α), myeloperoxidase (MPO), malondialdehyde (MDA) and superoxide dismutase (SOD), were examined. The results showed that Melilotus extract had a marked effect on the pathological manifestation of lung tissue and lung inflammatory response, the upregulation of TIPE2, HO-1 and IκB expression, and the inhibition of TLR4 and NF-κB activities. In addition, following treatment with Melilotus extract, the model animals demonstrated decreased levels of MPO and MDA as well as increased levels of SOD. In conclusion, these results indicated that Melilotus extract may be a potential therapeutic agent for the treatment of CLP-induced lung injury, the mechanism of which proceeded via inflammation- and oxidation-associated pathways by increasing TIPE2 expression. [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]

In recent years, agricultural producers and non-governmental organizations and agencies have restored thousands of hectares of cropland to grassland in the Great Plains of the United States. However, little is known about the relationships between richness and seeding density in these restorations and resistance to invasive plant species. We assessed the effects of richness and seeding density on resistance to invasive and other unseeded plant species in experimental tallgrass prairie plots in central Nebraska. In 2006, twenty-four 55 m x 55 m plots were planted with six replicates in each of four treatments: high richness (97 species typically planted by The Nature Conservancy), at low and high seeding densities, and low richness (15 species representing a typical Conservation Reserve Program mix, CP25), at low and high seed ng densities. There was a significant negative relationship between richness and basal cover of unseeded perennial forbsllegumes and unseeded perennial/annual grasses, abundance of bull thistle (Cirsium vulgare), and the number of inflorescences removed from smooth brome (Bromus inermis) transplants. Invasion resistance may have been higher in the high richness treatments because of the characteristics of the dominant species in these plots or because of greater interspecific competition for limiting resources among forbs/legumes with neighboring plants belonging to the same functional group. Seeding density was not important in affecting invasion resistance, except in the cover of unseeded grasses. Increasing seed mix richness may be more effective than increasing the seeding density for decreasing invasion by unseeded perennial species, bull thistle, and smooth brome. [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]

Background and aims: Plant productivity in drylands is frequently co-limited by water and nutrient availability, and thus is expected to be influenced by ongoing changes in rainfall regime and atmospheric nutrient deposition. Roadside grasslands are widespread worldwide, represent ecologically meaningful examples of highly dynamic anthropogenic ecosystems, and are well suited to investigate global change effects on plant performance. We evaluated the effects of changes in water and nutrient availability on the relative dominance and physiological performance of Bromus rubens, Carduus tenuifolius and Melilotus officinalis, which belong to contrasting functional groups (grasses, non-legume forbs and legumes, respectively). Methods: We conducted a factorial field experiment in two semiarid roadside grasslands in central Spain with the following factors: watering (no water addition vs. watering with 50% of the monthly total precipitation median) and fertilization (no fertilization vs. addition of 80 kg N ha year). The cover of the species evaluated, was surveyed over a 2-year period. Plant isotopic composition (leaf δC and δO) and nutrient concentrations (foliar N, P and K) were used to assess plant ecophysiological performance. Results: Carduus was able to cope with lower water availability levels through stomatal adjustments without a significant reduction in its relative dominance. The relative dominance of Bromus was negatively affected by even moderate water stress, although elevated nutrient deposition buffered the adverse impact of drought through a nutrient-mediated enhancement of plant water use efficiency. Increased nutrient availability strongly decreased the relative dominance of Melilotus, irrespective of water availability. Conclusions: Species-specific physiological mechanisms of adjustment to treatments suggest that plant communities in roadside grasslands will not respond as a unit to global environmental change. The characterization of species-specific responses to major global change drivers may improve predictions about the future dynamics of plant communities in novel ecosystems such as roadside slopes. [ABSTRACT FROM AUTHOR]

In ancient Chinese history, the Western Zhou Dynasty has long been renowned for having expanded its control and territory into many other states. However, historical documents and archaeological records of this period are limited; thus the early history of the Western Zhou Dynasty's operation in eastern China and its establishment of the Qi and Lu states have been unclear. The discovery of the Chenzhuang city site in Gaoqing County, Shandong Province, with chariot-horse pits, an altar and bronze vessels with inscriptions, adds a new line of evidence for studying the history of this period. However, with no direct evidence, the nature of the city site is controversial. Plant remains, especially a large number of sweet clover seeds, recovered from this site by systematic archaeobotanical methods provide an important source of information for research into the site's function. Considering that modern sweet clover is superior fodder for horses and the sweet clover seeds from the Chenzhuang site coexist with chariot-horse pits and horse remains, it is suggested these sweet clover seeds might represent the fodder of battle steeds. This suggestion supports the opinion of those who believe the Chenzhuang city site was once an important military city of the Western Zhou Dynasty in eastern China. [ABSTRACT FROM AUTHOR]

• Aerenchymatous phellem (secondary aerenchyma) has rarely been studied in roots. Its formation and role in internal aeration were evaluated for Melilotus siculus, an annual legume of wet saline land. • Plants were grown for 21 d in aerated or stagnant (deoxygenated) agar solutions. Root porosity and maximum diameters were measured after 0, 7, 14 and 21 d of treatment. Phellem anatomy was studied and oxygen (O2) transport properties examined using methylene blue dye and root-sleeving O2 electrodes. • Interconnecting aerenchymatous phellem developed in hypocotyl, tap root and older laterals (but not in aerial shoots), with radial intercellular connections to steles. Porosity of main roots containing phellem was c. 25%; cross-sectional areas of this phellem were threefold greater for stagnant than for aerated treatments. Root radial O2 loss was significantly reduced by complete hypocotyl submergence; values approached zero after disruption of hypocotyl phellem below the waterline or, after shoot excision, by covering hypocotyl phellem in nontoxic cream. • Aerenchymatous phellem enables hypocotyl-to-root O2 transport in M. siculus. Phellem increases radially under stagnant conditions, and will contribute to waterlogging tolerance by enhancing root aeration. It seems likely that with hypocotyl submerged, O2 will diffuse via surface gas-films and internally from the shoot system. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the orally administered combination of flavonoids desmin and troxerutin with Centella asiatica and Melilotus for the treatment of diabetic cystoid macular edema (CME) without macular thickening. Methods: In this prospective, interventional, controlled study, 40 consecutive patients with type 2 diabetes and CME without macular thickening at optical coherence tomography were randomized into 2 groups of 20 subjects each (treatment and control groups). The treatment group received an oral combination of desmin (300 mg/day) and troxerutin (300 mg/day) with C. asiatica (30 mg/die) and Melilotus (160 mg/die) for 14 months. Best collected visual acuity, central retinal thickness at optical coherence tomography, retinal sensitivity (RS), and stability of fixation at microperimetry were measured at baseline and monthly for 14 months. Results: In both groups, mean best collected visual acuity, central retinal thickness, and stability of fixation did not show differences during follow-up ( P > 0.05). At month 14, the RS was greater in the treated group ( P = 0.01) and was significantly reduced in the control group only ( P < 0.001). Five eyes in the study group showed disappearance of the intraretinal cysts after a mean time of 3.5 ± 0.3 months, which persisted in the following months. These 5 eyes presented a greater RS at each follow-up visit when compared with the control group ( P < 0.05). Anatomic improvement was never reported in the control group. Conclusions: The orally administered combination of flavonoids, C. asiatica, and Melilotus could be beneficial in preserving RS in diabetic CME without macular thickening. [ABSTRACT FROM AUTHOR]

This paper describes the range in coumarin concentrations at 90% flowering stage in 149 accessions belonging to 15 Melilotus species grown in a genetic resources field characterisation experiment in Adelaide, South Australia, and determines coumarin concentrations in Melilotus species grown at two contrasting field sites in South Australia (Kybybolite and Keith). In the genetic resources characterisation experiment, the mean coumarin content ranged from 0.06 to 0.753% of dry matter. M. segetalis, M. dentatus, M. sulcatus, M. siculus and M. infestus recorded low (0.06 to 0.113%) coumarin levels while moderate levels (0.332-0.753%) were registered in the other species. The coumarin levels at Kybybolite and Keith sites ranged from 0.095 to 0.943% amongst M. indicus accessions compared to M. siculus (0.007-0.100%) and M. sulcatus (0.007-0.810%). No coumarin was detected in a M. segetalis accession at these two sites. Accessions of M. siculus and an accession of M. segetalis (SA 36979) and of M. sulcatus (SA 40019) could be potential candidates as pasture legumes that can combine tolerance of both salinity and waterlogging, and acceptably low concentrations of coumarin. [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]

Most research on the ecology of PAH degrading bacteria in the rhizosphere has focused on individual strains that grow on specific PAHs. Thus, there are fundamental questions as to importance of microbial consortia for PAH degradation in the plant rhizosphere. The study reported here characterized cultivable pyrene degrading rhizoplane microbial communities from two different plant species using a root printing technique on agar plates. Colonies were revealed by formation of clearing zones on medium containing a thin film of pyrene on the surface of a mineral nutrient agar. Prints of the rhizoplane colonies were obtained from roots of Melilotus officinalis (sweet yellow clover) and Andropogon gerardii (big bluestem) plants. Phylogenetic characterizations of selected pyrene degrading colonies were assessed by PCR-DGGE and DNA sequencing. Results showed that different populations of cultivable pyrene degraders were obtained from representative consortia that were examined. Many of the PAH degrading consortia consisted of mixtures of bacterial species that were unable to degrade pyrene by themselves. While this study focused on culturable PAH degraders, the results suggest that pyrene degradation in the rhizosphere commonly involves the activity of bacterial consortia in which various species of bacteria interact to achieve PAH degradation. [ABSTRACT FROM AUTHOR]

Certain plant species promote biodegradation of polycyclic aromatic hydrocarbons (PAHs), but few studies have examined the microbial populations that are associated with the rhizoplane of these plants. In this study, the bacterial composition of the rhizoplane were characterized for four plant species during in soils with different histories of exposure to PAH and in the presence or absence of a pyrene spike at 100 mg kg-1 pyrene. Three of the plant species including Andropogon gerrardii, Panicum coloratum and Melilotus officinalis were known to stimulate PAH degradation. Wheat (Triticum aestivum) was used as a reference species. Results showed that after 90 days, approximately 45% of the pyrene spike disappeared from soil without plants. In contrast, cultivation of plants resulted in 95% disappearance of pyrene. There were no significant differences in the extent of pyrene disappearance for different plants. In all cases, 16S rRNA gene profiles of the rhizoplane were less complex in the pyrene-spiked soils, suggesting that richness and evenness of the predominant bacteria were reduced. Our results show that pyrene contamination results in significant shifts in the composition of rhizosphere bacterial communities that are still further influenced by the plant species and prior exposure history to PAH contamination. [ABSTRACT FROM AUTHOR]

This study examines the impact of the exotic nitrogen-fixing legume Melilotus officinalis (L.) Lam. on native and exotic species cover in two Great Plains ecosystems in Badlands National Park, South Dakota. Melilotus is still widely planted and its effects on native ecosystems are not well studied. Melilotus could have direct effects on native plants, such as through competition or facilitation. Alternatively, Melilotus may have indirect effects on natives, e.g., by favoring exotic species which in turn have a negative effect on native species. This study examined these interactions across a 4-year period in two contrasting vegetation types: Badlands sparse vegetation and western wheatgrass ( Pascopyrum smithii) mixed-grass prairie. Structural equation models were used to analyze the pathways through which Melilotus, native species, and other exotic species interact over a series of 2-year time steps. Melilotus can affect native and exotic species both in the current year and in the years after its death (a lag effect). A lag effect is possible because the death of a Melilotus plant can leave an open, potentially nitrogen-enriched site on the landscape. The results showed that the relationship between Melilotus and native and exotic species varied depending on the habitat and the year. In Badlands sparse vegetation, there was a consistent, strong, and positive relationship between Melilotus cover and native and exotic species cover suggesting that Melilotus is acting as a nurse plant and facilitating the growth of other species. In contrast, in western wheatgrass prairie, Melilotus was acting as a weak competitor and had no consistent effect on other species. In both habitats, there was little evidence for a direct lag effect of Melilotus on other species. Together, these results suggest both facilitative and competitive roles for Melilotus, depending on the vegetation type it invades. [ABSTRACT FROM AUTHOR]

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]

This study is focused on the allelopathic interference of Melilotus neapolitana, an annual stenomediterranean species frequently occurring in the herbaceous plant community of the Mediterranean macchia, on three coexisting species of the Mediterranean herbaceous plant community. The ethereal and methanol extracts of the plant led to the isolation of 11 allelochemicals: coumarin, cis- and trans-melilotoside, the dihydromelilotoside, seven flavone glycosides, as well as the inactive β-sitosterol, a C13-norterpene glucoside and a polyphenol. All the structures have been elucidated on the basis of their spectroscopic features. The organic extracts and all the pure compounds have been assayed for their allelopathic activity on three coexisting species, Petrorhagia velutina, Dactylis hispanica, and Phleum subulatum. The cluster analysis has shown a clear structure-activity relationship, by evidencing four main groups of compounds with a specific effect patterns. Coumarin, the most abundant compound both in the plant extracts and soil, is found to be highly phytotoxic on all the tested species. As for the flavone glycosides, it is shown that aglycones play an important role due to their bioactivity. [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]

Identifying forage species that are productive in saline environments is an important research priority in many areas of the world affected by salinity. The salt and waterlogging tolerances of 19 species of Melilotus were evaluated in a series of glasshouse experiments. Measurements taken on each species included: dry matter (DM) production, root growth and development, shoot ion (Na+, K+ and Cl−) concentrations, root porosity, and in vitro estimates of nutritive value. Research on several species was restricted because of their potential as weed risks. Of the remaining species, M. siculus (syn. M. messanensis), an annual species, showed high relative salt and waterlogging tolerances, good DM production under non-stressed and stressed (saline and hypoxic) conditions, a high level of root porosity under stagnant conditions, low tissue ion (Na+, Cl−) concentrations, and a reasonable dry matter digestibility content (range 66–69%) under highly saline conditions. M. sulcatus ssp. segetalis and M. indicus were also identified as species with good DM production and tolerance to salinity and waterlogging stresses. Further weed risk assessments and field trials on these species are required before they can be promoted for use as pasture forages on saline areas. [ABSTRACT FROM AUTHOR]

Semelil (ANGIPARS™), a novel herbal-based compound containing extract of Melilotus officinalis, was formulated for treatment of chronic wounds, especially diabetic foot ulcer. The purpose of this study was to investigate safety and toxicity effects of intramuscular administration of Semelil in dogs. Preliminary one-month study with Semelil was performed on 8 male and female dogs divided into 2 groups, test and control four animals each. Semelil was administered intramuscularlyat a dose of 0.07 ml/kg body wt. once a day to the animals of the test group, while the control group received sterile saline. During experiments, general state of the animals including the dynamics of body weight changes, appetite, motor activity and behavior, hair condition, ECG parameters, rectal temperature of animals and data of hematological and biochemical tests were monitored for signs of toxicity and side-effects. Finally, morphology and histology analyses were performed using standard methods. No adverse health or toxicity effects were observed through the course of the study. No damaging consequences of Semelil injections on the functional state of main organs of the experimental animals were found. This observation gave a good evidence of a favorable safety profile compatible with potential therapeutic use of Semelil. [ABSTRACT FROM AUTHOR]

Semelil (ANGIPARS™), an herbal formulation containing Melilotus officinalis extract, is a novel compound being developed for treatment of chronic wounds, particularly diabetic foot ulcers. The purpose of this study was to investigate toxicological, pharmacological, and pathomorphological effects of I.M. and I.P. administration of Semelil in animals. The acute toxicity parameters of Semelil diluted in normal saline (l:10 or 1:5) were determined after a single injection into BALB/c mice and Wistar rats in two steps. First, the LD50 was approximately assessed and then the precise lethal dose indices were estimated by the probit-analysis method. Specific single-dose effects of Semelil were monitored for clinical signs of toxicity, including general state of the animals, changes in their behavior, hematological and biochemical parameters for 14 days after drug administration. Then, subacute-chronic toxicity was evaluated in rats treated with Semelil for 3 months. In acute toxicity study, the calculated LD50 for drug diluted at 1:5 was in the range of 44-52 ml/kg. The adverse effects at drug doses close to the LD50 included depressed mood, narcosis, and sleep. No adverse pharmacological or toxicological effects of the drug diluted at I:10 and administered in the single-dose (25-50 ml/kg body wt.) or chronically (daily doses of 0.07 and 0.21 ml/kg body wt.) were noted. Thus, the animal studies demonstrated a favorable safety profile for the phytotherapeutic Semelil. [ABSTRACT FROM AUTHOR]

We compared the native bees visiting the flowers of three species of invasive plants, saltcedar (Tamarix spp.) and white and yellow sweet clover (Melilotus albus, M. officinalis), with those visiting seven concurrently blooming native plant species in mid-summer at three sites in Capitol Reef National Park, Utah. Overall, as many total species of bees visited the flowers of the three invasive plant species as visited the seven natives. On average, invasive species were visited by twice as many bee species as were natives. With a single exception, visitors of invasives were generalist bees, rather than specialists. Colletes petalostemonis, the only native legume specialist recorded, was an abundant forager on the flowers of both species of Melilotus, demonstrating that at least some specialist bees will move to invasive plants that are closely related to their usual hosts. Species abundant on the flowers of invasives tended to collect both pollen and nectar, suggesting that bees are using pollen of Tamarix and Melilotus to provision their offspring. We argue that invasives with entomophilous flowers are unlikely to either facilitate the reproduction of uncommon native plants or consistently compete with them for pollinators. Rather, they are likely, overtime, to selectively increase the carrying capacity and population size of native bees, specifically generalists, and specialists of closely related plant species. [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]

With a view to optimizing of the quality control of sweetclover herbs and related preparations containing coumarins among the active substances, methods for the isolation and analysis of compounds of this class — in particular, coumarin and furocoumarin — are reviewed. The group of possible analytical methods includes gravimetric, titrimetric, photocolorimetric, and polarographic analysis, and the more recently developed spectroscopic (UV and IR), fluorimetric, and chromatographic (GC and HPLC) techniques. [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]

The article focuses on the registration of N30-N56, N741, N743, N745, N747, U362, U363, U367, U369-U374, U389.U394, U396-U398, and U500 sweetclover genetic stocks. Forty-nine white-flowered sweetclover (Melilotus alba Medik.) genetic stocks, a yellow-flowered sweetclover genetic stock, were developed jointly by the U.S. Department of Agriculture-Agricultural Research Service and the Agricultural Research Division, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln, Nebraska and were jointly released in May 2004. The genetic stocks, which contain unique combinations of genes and traits, were developed over more than three decades of cooperative sweet- clover genetic research. The development of 16 lines involved both annual and biennial forms of M. alba, and the greenhouse conditions under which seed of these lines were produced did not permit distinguishing between these forms. U389 is an annual line that was derived from a single plant of the introduction, P1165554, mentioned above. All of the other U-numbered lines were developed following treatment of U389 seed with ethyl methanesulfonate. Seed should be scarified before planting. It is requested that appropriate recognition be made if these genetic stocks contribute to research or the development of a new breeding line or cultivar.

Many recent studies suggest that more diverse communities are more resistant to invasion. Community characteristics that most strongly influence invasion are uncertain, however, due to covariation of diversity with competition and crowding. We examined separately the effects of species richness and dominance on invasion by an exotic legume, Melilotus officinalis, in intact, native Kansas grassland. We manipulated dominance of C4 grasses by reducing their abundance (i.e. ramet densities) by ∼25 and 50%. In addition, richness was reduced by removing species that were mainly rare and uncommon as might be expected with environmental changes such as drought and fragmentation. In both years of the study (2001–2002), invasibility, measured as peak establishment of Melilotus, was not affected by a 3-fold reduction in species richness, nor was there an interaction between loss of species and reduced dominance on invasion. In contrast, reductions in abundance of the dominants significantly reduced invasibility of the grassland plots in both years. Because the abundance of dominants was highly correlated with measures of competition (i.e. ratio of dominant biomass to total biomass) and crowding (total stem densities), this pattern was opposite to that expected if competition were indeed limiting invasion. Rather, invasion appeared to be facilitated by the dominant species, most likely because reduced dominance increased environmental stress. Our results suggest that dominance is the key community characteristic determining invasibility, because highly competitive and space-filling species can either enhance or reduce susceptibility to invasion depending on whether dominants create a more competitive environment or alleviate stressful conditions. [ABSTRACT FROM AUTHOR]

Invasion of nitrogen-fixing non-native plant species may alter soil resources and impact native plant communities. Altered soils may be the driving mechanism that provides a suitable environment to facilitate future invasions and decrease native biodiversity. We hypothesized that Melilotus invasion would increase nitrogen availability and produce soil microclimate and biochemical changes, which could in turn alter plant species composition in a montane grassland community. Our research addressed the effects of white and yellow sweet clover ( Melilotus officinalis and M. alba) invasion on soil characteristics and nitrogen processes in the montane grasslands in Rocky Mountain National Park. We sampled soil in replicate sites of Melilotus-invaded and control (non-invaded) patches within disturbed areas in montane grassland habitats. Soil composites were analysed for available nitrogen, net nitrogen mineralization, moisture, carbon/nitrogen (C : N ratio), texture, organic matter and pH. Data were recorded at three sample dates during the growing seasons of 1998 and 1999. Contrary to our expectations, we observed lower nitrogen availability and mineralization in invaded patches, and differences in soil moisture content and soil C : N. Soil C : N ratios were higher in invaded plots, in spite of the fact that Melilotus had the lowest C : N ratios of other plant tissue analysed in this study. These findings provide land managers of natural areas with a better perspective on the possibilities of nitrogen-fixing species impact on soil nutrient levels. [ABSTRACT FROM AUTHOR]

Exotic (nonnative) invasion, often fostered by anthropogenic disturbances, can be detrimental to the biodiversity of indigenous plant communities. We examined the impact of two exotic species, Melilotus officinalis and M. alba (yellow and white sweet clover) in the montane grassland community in Rocky Mountain National Park to determine (1) whether native and exotic plant diversity differs between patches within grasslands that are invaded by Melilotus species and patches that are not invaded (control patches) and (2) whether the presence of Melilotus species are associated with specific exotic species. Variables that were recorded included species richness, species composition, and percent cover in invaded and control patches at multiple spatial scales. The results showed that more exotic, annual/biennial, and forb species occurred within patches invaded by Melilotus species, while more native, perennial, and grass species occurred in nearby control patches. Moreover, the invaded patches had several exotic species that were not found in control patches, whereas certain native species were only found in control patches. In some instances, the presence of Melilotus in the native community appeared unrelated to disturbance; some colonies were in seemingly undisturbed meadows well beyond disturbance edges. The data also showed that Melilotus species spread beyond original mapped boundaries in a span of two seasons. [ABSTRACT FROM AUTHOR]

Examines the mechanisms of Nod factor perception and signaling transduction of Medicago truncatula. Identification of a new locus and nodulation-signaling pathway 2; Reduction of root hair deformation response; Absence of infection and cortical cell division following Sinorhizobium meliloti inoculation.

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]

Offers a look at a study that reported chemical and biological data supporting the identification of lumichrome as the described Sinorhizobium meliloti factor that increases alfalfa root respiration. Materials and methods; Biological tests with lumichrome; Optimization of the production of compound D; Purification of compounds D and Y; Identification of compounds D and Y; Biological activity of lumichrome; Discussion.