Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Medicago sativa”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2002

Metabolic profiling of saponins in Medicago sativa and Medicago truncatula using HPLC coupled to an electrospray ion-trap mass spectrometer.

Triterpene saponins isolated from Medicago sativa (alfalfa) and Medicago truncatula roots were separated, profiled and identified using an optimized, reversed-phase HPLC with on-line photodiode array detection and electrospray ionization mass spectrometry method (HPLC/PDA/ESI/MS). ESI source polarity and solvent conditions were compared. The effects of these parameters on mass spectral attributes were determined. Ion structures were confirmed using tandem mass spectrometry (MS/MS). Fifteen saponins were identified in alfalfa (cultivars Apollo, Radius, and Kleszczewska) based upon negative-ion HPLC/PDA/ESI/MS, HPLC/PDA/ESI/MS/MS and literature data. In addition, the identification of two new malonated saponins in alfalfa are proposed. Negative-ion HPLC/PDA/ESI/MS and HPLC/PDA/ESI/MS/MS spectra were utilized along with HPLC retention times to profile and identify 27 saponins in M. truncatula (cultivar Jemalong, A17). M. truncatula yielded a much more complex mixture of saponins than observed for alfalfa. The authors are not aware of any previous reports identifying saponin glycosides in M. truncatula.

Chromatography, High Pressure Liquid↗
PubMed2003

Kinetics and strain specificity of rhizosphere and endophytic colonization by enteric bacteria on seedlings of Medicago sativa and Medicago truncatula.

The presence of human-pathogenic, enteric bacteria on the surface and in the interior of raw produce is a significant health concern. Several aspects of the biology of the interaction between these bacteria and alfalfa (Medicago sativa) seedlings are addressed here. A collection of enteric bacteria associated with alfalfa sprout contaminations, along with Escherichia coli K-12, Salmonella enterica serotype Typhimurium strain ATCC 14028, and an endophyte of maize, Klebsiella pneumoniae 342, were labeled with green fluorescent protein, and their abilities to colonize the rhizosphere and the interior of the plant were compared. These strains differed widely in their endophytic colonization abilities, with K. pneumoniae 342 and E. coli K-12 being the best and worst colonizers, respectively. The abilities of the pathogens were between those of K. pneumoniae 342 and E. coli K-12. All Salmonella bacteria colonized the interiors of the seedlings in high numbers with an inoculum of 10(2) CFU, although infection characteristics were different for each strain. For most strains, a strong correlation between endophytic colonization and rhizosphere colonization was observed. These results show significant strain specificity for plant entry by these strains. Significant colonization of lateral root cracks was observed, suggesting that this may be the site of entry into the plant for these bacteria. At low inoculum levels, a symbiosis mutant of Medicago truncatula, dmi1, was colonized in higher numbers on the rhizosphere and in the interior by a Salmonella endophyte than was the wild-type host. Endophytic entry of M. truncatula appears to occur by a mechanism independent of the symbiotic infections by Sinorhizobium meliloti or mycorrhizal fungi.

Enterobacteriaceae↗
PubMed1997

Pancreatic and extra-pancreatic effects of the traditional anti-diabetic plant, Medicago sativa (lucerne).

Medicago sativa (lucerne) is used as a traditional plant treatment of diabetes. In the present study, administration of lucerne in the diet (62.5 g/kg) and drinking water (2.5 g/l) reduced the hyperglycaemia of streptozotocin-diabetic mice. An aqueous extract of lucerne (1 mg/ml) stimulated 2-deoxy-glucose transport (1.8-fold), glucose oxidation (1.7-fold) and incorporation of glucose into glycogen (1.6-fold) in mouse abdominal muscle. In acute 20 min tests, 0.25-1 mg/ml aqueous extract of lucerne evoked a stepwise 2.5-6.3-fold stimulation of insulin secretion from the BRIN-BD11 pancreatic B-cell line. This effect was abolished by 0.5 mM-diazoxide, and prior exposure to extract did not affect subsequent stimulation of insulin secretion by 10 mM-L-alanine, thereby negating a detrimental effect on cell viability. The effect of extract was potentiated by 16.7 mM-glucose and by 1 mM-3-isobutyl-1-methylxanthine. L-Alanine (10 mM) and a depolarizing concentration of KCl (25 mM) did not augment the insulin-releasing activity of lucerne. Activity of the extract was found to be heat stable and largely acetone insoluble, and was enhanced by exposure to acid and alkali (0.1 M-HCl and NaOH) but decreased 25% with dialysis to remove components with molecular mass < 2000 Da. Sequential extraction with solvents revealed insulin-releasing activity in both methanol and water fractions indicating a cumulative effect of more than one extract constituent. The results demonstrate the presence of antihyperglycaemic, insulin-releasing and insulin-like activity in the traditional antidiabetic plant, Medicago sativa.

1-Methyl-3-isobutylxanthine↗
PubMed2003

Structural changes induced by NaCl in companion and transfer cells of Medicago sativa blades.

Medicago sativa var. Gabes is a perennial glycophyte that develops new shoots even in high salinity (150 mM NaCl). In the upper exporting leaves, K(+) is high and Na(+) is low by comparison with the lower leaves, where Na(+) accumulation induces chlorosis after 4 weeks of NaCl treatment. By secondary ion mass spectroscopy, a low Na(+)/K(+) ratio was detected in the phloem complex of blade veins in these lower leaves. By transmission electron microscopy, the ultrastructural features were observed in the phloem complex. In the upper leaves of both control and NaCl-treated plants, companion cells in minor veins were found to be transfer cells. These cells may well be involved in the intravenous recycling of ions and in Na(+) flowing out of exporting leaves. Under the effect of NaCl, companion cells in the main veins develop transfer cell features, which may favor the rate of assimilate transport from exporting leaves toward meristems, allowing the positive balance necessary for the survival in salt conditions. These features no longer assist the lower leaves when transfer cells are necrotized in both minor and main veins of NaCl-treated plants. As transfer cells are the only degenerating phloem constituent, our observations emphasize their role in controlling nutrient (in particular, Na(+)) fluxes associated with the stress response.

Cell Wall↗
PubMed2005

Cellular damage induced by cadmium and mercury in Medicago sativa.

Alfalfa (Medicago sativa) plantlets were exposed to Cd or Hg to study the kinetics of diverse stress indexes. In the so-called beaker-size hydroponic system, plantlets were grown in 30 microM of Cd or Hg for 7 d. Oxidative stress took place and increased over time, a linear response being observed with Cd but not with Hg. To improve the sensitivity of the stress assays used, a micro-assay system, in which seedlings were exposed for 24 h, was developed. Phytotoxicity of metals, quantified as growth inhibition, was observed well before there was any change in the non-protein thiol tissue concentration. When measured with conventional techniques, oxidative stress indexes did not show significant variation. To trace early and small plant responses to Cd and Hg, a microscopic analysis with novel fluorescent dyes, which had not yet been exploited to any significant extent for use in plants, was conducted. These fluorescent probes, which allowed minute cellular responses to 0, 3, 10, and 30 microM of both metals to be visualized in the roots of the alfalfa seedlings, were: (i) 2',7'-dichlorofluorescin diacetate that labels peroxides; (ii) monochlorobimane that stains reduced glutathione/homoglutathione (GSH/hGSH); and (iii) propidium iodide that marks nuclei of dead cells. Oxidative stress and cell death increased after exposure for 6-24 h to Cd and Hg, but labelling of GSH/hGSH decreased acutely. This diminution might be the result of direct interaction of GSH/hGSH with both Cd and Hg, as inferred from an in vitro conjugation assay. Therefore, both Cd and Hg not only compromised severely the cellular redox homeostasis, but also caused cell necrosis. In plants treated with 1 mM L-buthionine sulphoximine, a potent inhibitor of GSH/hGSH synthesis, only the oxidative stress symptoms appeared, indicating that the depletion of the GSH/hGSH pool was not sufficient to promote cell death, and that other phytotoxic mechanisms might be involved.

Cadmium↗
PubMed2006

Metabolic adaptations to mercury-induced oxidative stress in roots of Medicago sativa L.

Alfalfa (Medicago sativa) roots were treated with mercuric ions in a concentration- and time-dependent manner, and lipid peroxidation was studied biochemically as well as histochemically along with other physiological responses. Histochemical staining with Schiff's reagent and Evans blue revealed that the peroxidation of membrane lipids and loss of plasma membrane integrity in Hg-treated roots occurred in the meristem and the elongation zone. The histochemical observations were supported by the quantitative determinations of thiobarbituric acid reactive substances (TBARS). However, under the mercuric ions stress, the alfalfa plants showed no significant alteration of hydrogen peroxide in roots. Analysis of lipoxygenase activity by non-denaturing polyacrylamide gel electrophoresis (PAGE) showed that there were two isoforms in the root of alfalfa plants, but they showed quite different patterns under the Hg exposure. Also, using non-denaturing PAGE, activities of superoxide dismutase (SOD) and peroxidase (POD) were determined in roots after treatment with Hg ions. The total activities of SOD and POD increased in roots after Hg treatment of roots. Activity of ascorbate peroxides (APX) was stimulated at relatively high concentration of Hg (40microM), and after prolonged Hg exposure (20microM, 24h). In contrast, glutathione reductase activity was depressed at higher concentrations of Hg (10-20microM). Treatments of seedlings with 10-40microM Hg decreased the ascorbate and glutathione amounts but increased total non-protein thiols. The above results indicated that Hg exerted its toxic effect on the root growth of alfalfa by induction of oxidative stress.

Electrophoresis, Polyacrylamide Gel↗
PubMed2002

The mode of action of cell wall-degrading enzymes and their interference with Nod factor signalling in Medicago sativa root hairs.

Medicago sativa L. (alfalfa) root hairs respond to Nod factors [NodRm-IV(C16:2,S)] in a host-specific manner with depolarization and rapid ion fluxes. Protoplasts prepared from these cells using the cell wall-digesting enzymes pectolyase and cellulase do not, or to a rather small extent, respond to Nod factors. In an effort to understand this activity loss we analyzed the mode of action of both enzymes with respect to their effects on the root hairs as well as their interference with the Nod factor response. (i) In the presence of the enzymes, Nod factor at saturating concentrations neither depolarized the plasma membrane of root hairs nor caused ion fluxes. Even after removal of the enzymes, Nod factor responses were strongly refractory. (ii) After a lag-phase of 12-18 s, pectolyase depolarized the plasma membrane, alkalized the external space, acidified the cytosol and increased the cytosolic Ca(2+) activity. (iii) Cellulase, without a lag-phase, depolarized the plasma membrane, acidified the cytosol, but only marginally increased the cytosolic Ca(2+) activity. Unlike pectolyase, the cellulase response was only weakly refractory to a second addition. (iv) Neither enzyme increased the membrane conductance, but pectolyase inhibited the H(+)-pump. (v) Pectolyase shows all the signs of an elicitor, while cellulase yields a mixed response. (vi) Denatured enzymes yielded strong effects similar to those of untreated enzymes. We conclude that the effects shown do not originate from enzymatic activity, but from interactions of the proteins with cell wall or plasma membrane constituents. It is further concluded that these enzymes (pectolyase more so than cellulase) trigger defense-related signal pathways, which makes protoplasts prepared with such enzymes unsuitable for studies of symbiotic or defense-related signalling.

Calcium↗
PubMed1988

Ozone effects on growth and assimilate partitioning in alfalfa, Medicago sativa L.

Alfalfa (Medicago sativa L.) were exposed to O(3) concentrations varying between 118 x 10(-6) microg cm(-3) (0.06 ppm) and 157 x 10(-6) microg cm(-3) (0.08 ppm) for 6 h per day 5 days per week for several weeks. Typical plants were sacrificed weekly, and growth parameters were measured. O(3) reduced overall growth, relative growth rates and unit leaf rates in alfalfa before it was cut, indicating that O(3) had reduced photosynthesis. However, after the alfalfa was cut, these same parameters indicated that in some cases, O(3)-stressed plants had greater photosynthetic rates than controls during regrowth. O(3) also altered dry matter partitioning. Roots were most affected, followed by leaves and stems, respectively. In general, O(3) reduced photosynthate production and reduced the proportion of photosynthate partitioned to roots relative to leaves and stems. This could reduce starch reserves in alfalfa, and be detrimental to stand longevity. However, the post-cutting study indicated that at least some alfalfa cultivars may be able to acclimate to O(3)-stress, though plants did not fully recover from pre-cutting differences.

Journal Article↗
PubMedDate not supplied

Stimulation of pancreatic lipase activity by saponins isolated from Medicago sativa L.

Saponins isolated from Medicago sativa L. appeared to stimulate lipolytic activity and did not influence amylolytic or proteolytic activity of Neopancreatinum (extract of pancreatic enzymes: lipase, proteases and amylases). Saponins isolated from the aerial part of Medicago sativa L. were demonstrated to stimulate lipase activity more effectively than saponins separated from the root of this plant. When saponins were treated with 0.02 M HCl at 37 degrees C for 1 hour their lipase stimulation ability did not change. The saponins stimulated Neopancreatinum lipolytic activity more intensively in the presence of sodium cholate.

Amylases↗
PubMed1972

Photoperiodic Effects on the Emanation of Volatiles from Alfalfa (Medicago sativa L.) Florets.

Alfalfa (Medicago sativa L.) plants acclimated to photoperiods of 18 hours light, 6 hour dark in plant growth chambers exhibited a daily cyclic pattern of floret volatile emanation with a maximum emanation of about 6.5 nanograms of hydrocarbons/floret.30 minutes. This maximum was reached about 6 to 8 hours into the light period. After 8 hours of light, emanation of volatiles decreased rapidly to less than 0.1 ng/floret.30 min even though light and temperature remained constant. Under continuous illumination, only a small increase of volatile emanation occurred during the following 24 hours. It appeared that a dark period was necessary to promote floret volatile emanation. Floret volatile emanation was drastically affected for at least 7 days following a photoperiod change. A photoperiod change caused 6-fold concentration oscillations every 2 hours. The results are interpreted on the basis of a very active floral metabolism controlled by photoperiodically induced rhythms.

Journal Article↗
PubMed2004

Bioactivity of lipophilic metabolites from glandular trichomes of Medicago sativa against the potato leafhopper.

Medicago sativa cv. G98A is highly resistant to the potato leafhopper, Empoascafabae. Glandular trichome extracts from G98A were fractionated using flash chromatography and tested for settling deterrency against the potato leafhopper. A fraction of intermediate polarity exhibited strong, dose-dependent deterrency when applied to the surface of an artificial diet sachet. Deterrency was not detected, however, when the fraction was applied to the internal surface of the sachet membrane (i.e., when contact was limited to only the leafhoppers' stylets). Major components of the highly deterrent fraction, determined by gas chromatography-mass spectrometry, were a homologous series of fatty acid amides C(n)H(2n+1)NO (n = 19-23) and trace components were 12:0, 13:0, 14:0, 15:0, 16:0, 17:0, 18:0, and possibly 18:1 free fatty acids. Deterrency declined slightly, but was still strong, after fatty acids were removed from crude extracts. When the crude extracts were separated further, a fraction containing only the fatty acid amides was also deterrent. Activity increased when this fraction was supplemented with authentic (C12:0 through C18:0, and C18:1) free fatty acids. However, the authentic free fatty acids were not deterrent when tested without the lipophilic amides. Fatty acid amides and free fatty acids in trichomes of M. sativa G98A may synergize and together function in deterring settling by the potato leafhopper.

Amides↗
PubMed1999

Molecular characterisation and expression of a wound-inducible cDNA encoding a novel cinnamyl-alcohol dehydrogenase enzyme in lucerne (Medicago sativa L.)

A lucerne (alfalfa, Medicago sativa) stem cDNA library was screened with a cinnamyl-alcohol dehydrogenase (CAD) cDNA probe from tobacco (Nicotiana tabacum cv. Samsun). Two distinctly different cDNA clones (54% identical) were isolated and identified as putative CAD-encoding cDNAs by comparison of their nucleotide sequences with those of CAD-encoding DNA sequences from other plant species. One of the cDNAs, MsaCad2, was found to be 99.4% identical at the nucleotide level to the previously isolated lucerne cad cDNA which encodes a CAD isoform involved in lignin biosynthesis. The other cDNA, MsaCad1, has not been reported previously in lucerne, and encodes a protein related to the ELI3 class of elicitor-inducible defence-related plant proteins. The MsaCad1- and MsaCad2-encoded proteins were expressed in Escherichia coli and CAD1 was shown to be active with a range of cinnamyl, benzyl and aliphatic aldehyde substrates, while CAD2 was specific for the cinnamyl aldehydes only. Each of the respective genes is present as one or two copies. The MsaCad1 gene is expressed most actively in stem and floral tissue, whereas MsaCad2 is most actively expressed in stem, hypocotyl and root tissue. In stem tissue, expression of both genes occurs predominantly in internodes 4 and 5 (from the apex). MsaCad2, in contrast to MsaCad1, is not significantly expressed in the top three internodes of the stem. Both MsaCad1 and MsaCad2 are wound-inducible, and the wound-responsiveness of each gene is modulated by salicylic acid.

Alcohol Oxidoreductases↗
PubMed1988

Adenylate cyclase activity in a higher plant, alfalfa (Medicago sativa).

An adenylate cyclase activity in Medicago sativa L. (alfalfa) roots was partially characterized. The enzyme activity remains in the supernatant fluid after centrifugation at 105,000 g and shows in crude extracts an apparent Mr of about 84,000. The enzyme is active with Mg2+ and Ca2+ as bivalent cations, and is inhibited by EGTA and by chlorpromazine. Calmodulin from bovine brain or spinach leaves activates this adenylate cyclase.

Adenylyl Cyclase Inhibitors↗
PubMed1980

Purification and properties of alpha-D-mannosidase from the germinated seeds of Medicago sativa (alfalfa).

alpha-Mannosidase of Medicago sativa (alfalfa) was purified 1340-fold. The purification method included dialysis of the crude extract against a citrate/phosphate buffer, pH 3.9, (NH4)SO4 precipitation, hydroxyapatite chromatography, chromatography on Sephadex G-200 and finally a preparatory electrophoresis on polyacrylamide-gel gradient by Doly & Petek's [(1977) J. Chromatogr. 137. 69--81] method. Each step of purification was checked by polyacrylamide-gel disc electrophoresis. The purified enzyme showed a single band, corresponding to alpha-mannosidase activity. alpha-Mannosidase has a mol.wt. 230 000 as estimated by Hedrick & Smith's [(1968) Arch. Biochem. Biophys. 126, 155--164] method and also by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate by Weber & Osborn [(1969) J. Biol. Chem. 244, 4406--4412]. The enzyme comprises four subunits of different molecular weight. Optimum pH and Km values were determined with p-nitrophenyl alpha-D-mannoside as substrate. When incubated at a temperature between 20 and 62 degrees C before assay, alpha-mannosidase initially shows an increase in activity. alpha-Mannosidase is stable when the pH is about neutrality. It can be inactivated by several metal ions, including Zn2+. At a pH below 5 the enzyme undergoes irreversible inactivation. The presence of EDTA at acid pH considerably enhances the inactivation of the enzyme. This inactivation due to EDTA can be specifically reversed by incubation with Zn2+.

Cations↗
PubMed2002

Influence of summer sowing dates, N fertilization and irrigation on autumn VSP accumulation and dynamics of spring regrowth in alfalfa (Medicago sativa L.).

Herbage yield of alfalfa (Medicago sativa L.) depends on forage management or environmental conditions that change C and N resource acquisition, and endogenous plants factors such as root organic reserves and number of active meristems. The aim of this work is to study the influence of two sowing dates in summer (12 July or 9 August), N fertilization (0 or 100 kg ha(-1)) and/or irrigation applied during the first year of alfalfa establishment on (i) the accumulation of N organic reserves (soluble proteins and more specifically vegetative storage protein) in taproots during autumn, (ii) the number of crown axillary meristems present at the end of winter and (iii) the dynamics of spring shoot growth. Delaying the sowing date for one month reduced root growth and root N storage, especially vegetative storage proteins (VSP) during autumn. Irrespective of sowing dates, N fertilization did not affect root biomass, number of crown buds, total root N, root soluble protein or VSP concentrations. By contrast, water deficiency during alfalfa establishment in the early summer reduced both root growth and N reserve accumulation. When spring growth resumed, there is a significant linear relationship between leaf area development and soluble protein and VSP concentrations in taproots, and also the number of crown buds. The results showed that an early sowing date and adequate water status during the summer allowed alfalfa plants to accumulate N reserves by increasing taproot mass and soluble protein concentrations, especially VSPs. This resulted in rapid shoot regrowth rates the following spring.

Carbon↗
PubMed1992

High frequency, heat treatment-induced inactivation of the phosphinothricin resistance gene in transgenic single cell suspension cultures of Medicago sativa.

One descendant of the Medicago sativa Ra-3 transformant T304 was analysed with respect to the somatic stability of the synthetic phosphinothricin-N-acetyltransferase (pat) gene which was used as a selective marker and was under the control of the 5'/3' expression signals of the cauliflower mosaic virus (CaMV) gene VI. In order to quantify gene instability, we developed a system for culturing and regenerating individual cells. Single cell suspension cultures derived from T304 and the ancestral non-transgenic M. sativa cultivar Ra-3, were established. The cells were regenerated into monoclonal calli. In transgenic calli, the phosphinothricin (Pt)-resistance phenotype was retained after more than 2 months of non-selective growth. In contrast, up to 12% of the suspension culture cells grown under nonselective conditions and at constant temperature (25 degrees C) lost the herbicide-resistance phenotype within 150 days. Surprisingly, a heat treatment (37 degrees C), lasting for 10 days, during the culture period resulted in an almost complete (95%) loss of the Pt resistance of the suspension culture cells. However, the frequency of cell division was identical in cultures grown under normal and heat treatment conditions. A biochemical test revealed that no phosphinothricin-N-acetyltransferase activity was present in heat treated, Pt-sensitive cells. The resistance level of the Pt-sensitive transgenic cells was equivalent to that of the wild-type cells. A PCR analysis confirmed the presence of the pat gene in heat treated, Pt-sensitive cells. From these results it is concluded that the Pt resistance gene was heat-inactivated at a high frequency in the M. sativa suspension cultures.

Acetyltransferases↗