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PubMedDate not supplied

Flavonoids and phenol carboxylic acids in the oriental medicinal plant Astragalus membranaceus acclimated in Poland.

Astragalus membranaceus (Fisch.) Bunge has been was successfully acclimated in Central Europe. We report the content of isoflavones and some other polyphenolic compounds in roots and aerial parts that have been analyzed by means of TLC and HPLC. The total amount of isoflavones in leaves, was 0.55 mg g(-1) dry weight, and of the flavonols--up to 3.54 mg g(-1). In the roots isoflavonoid content was extremely variable, but reached 3.04 mg g(-1), whereas flavonols content was 0.49 mg g(-1).

Acclimatization↗
PubMed2005

Analysis of sulfur and selenium assimilation in Astragalus plants with varying capacities to accumulate selenium.

Several Astragalus species have the ability to hyperaccumulate selenium (Se) when growing in their native habitat. Given that the biochemical properties of Se parallel those of sulfur (S), we examined the activity of key S assimilatory enzymes ATP sulfurylase (ATPS), APS reductase (APR), and serine acetyltransferase (SAT), as well as selenocysteine methyltransferase (SMT), in eight Astragalus species with varying abilities to accumulate Se. Se hyperaccumulation was found to positively correlate with shoot accumulation of S-methylcysteine (MeCys) and Se-methylselenocysteine (MeSeCys), in addition to the level of SMT enzymatic activity. However, no correlation was observed between Se hyperaccumulation and ATPS, APR, and SAT activities in shoot tissue. Transgenic Arabidopsis thaliana overexpressing both ATPS and APR had a significant enhancement of selenate reduction as a proportion of total Se, whereas SAT overexpression resulted in only a slight increase in selenate reduction to organic forms. In general, total Se accumulation in shoots was lower in the transgenic plants overexpressing ATPS, PaAPR, and SAT. Root growth was adversely affected by selenate treatment in both ATPS and SAT overexpressors and less so in the PaAPR transgenic plants. Such observations support our conclusions that ATPS and APR are major contributors of selenate reduction in planta. However, Se hyperaccumulation in Astragalus is not driven by an overall increase in the capacity of these enzymes, but rather by either an increased Se flux through the S assimilatory pathway, generated by the biosynthesis of the sink metabolites MeCys or MeSeCys, or through an as yet unidentified Se assimilation pathway.

Arabidopsis↗
PubMed2006

Spatial imaging, speciation, and quantification of selenium in the hyperaccumulator plants Astragalus bisulcatus and Stanleya pinnata.

Astragalus bisulcatus and Stanleya pinnata hyperaccumulate selenium (Se) up to 1% of plant dry weight. In the field, Se was mostly present in the young leaves and reproductive tissues of both hyperaccumulators. Microfocused scanning x-ray fluorescence mapping revealed that Se was hyperaccumulated in trichomes in young leaves of A. bisulcatus. None of 10 other elements tested were accumulated in trichomes. Micro x-ray absorption spectroscopy and liquid chromatography-mass spectrometry showed that Se in trichomes was present in the organic forms methylselenocysteine (MeSeCys; 53%) and gamma-glutamyl-MeSeCys (47%). In the young leaf itself, there was 30% inorganic Se (selenate and selenite) in addition to 70% MeSeCys. In young S. pinnata leaves, Se was highly concentrated near the leaf edge and surface in globular structures that were shown by energy-dispersive x-ray microanalysis to be mainly in epidermal cells. Liquid chromatography-mass spectrometry revealed both MeSeCys (88%) and selenocystathionine (12%) inside leaf edges. In contrast, both the Se accumulator Brassica juncea and the nonaccumulator Arabidopsis thaliana accumulated Se in their leaf vascular tissues and mesophyll cells. Se in hyperaccumulators appears to be mobile in both the xylem and phloem because Se-treated S. pinnata was found to be highly toxic to phloem-feeding aphids, and MeSeCys was present in the vascular tissues of a S. pinnata young leaf petiole as well as in guttation fluid. The compartmentation of organic selenocompounds in specific storage areas in the plant periphery appears to be a unique property of Se hyperaccumulators. The high concentration of Se in the plant periphery may contribute to Se tolerance and may also serve as an elemental plant defense mechanism.

Astragalus Plant↗
PubMed1999

From flowering to dispersal: reproductive ecology of an endemic plant, Astragalus australis var. olympicus (Fabaceae).

Astragalus australis var. olympicus is an endemic plant of the Olympic Mountains, Washington. It is considered a Species of Concern by the U.S. Fish and Wildlife Service. This study focused on the reproductive biology of the plant from flower production through seed germination to identify possible weak points that might contribute to its rarity and impede its conservation. Most plants produced a large mean number of flowers and ovules (314.8 and 4106, respectively), but relatively few of these formed fruits and seeds (25.8 and 3.8%, respectively). In decreasing importance, ovules in fruits were lost to predation, seed abortion, and lack of fertilization. The percentages of these fates differed among sites and years. Excluding pollinators by bagging flowers reduced fruit set by ∼50%, but seed set per fruit and seed mass were unaffected. Germination was affected by scarification, temperature, and moisture availability. About 11% of seeds damaged by predispersal seed predators (weevil larvae) remained viable and were released from dormancy. I hypothesize that predispersal seed predation (over 80% at one site) has a negative effect on population growth. Conservation of this species could benefit from improved fruit set and decreased seed predation.

Journal Article↗
PubMed1989

Toxicosis in pigs fed selenium-accumulating Astragalus plant species or sodium selenate.

Three groups of 5 pigs each were fed a high selenium (Se) diet by mixing either Astragalus praelongus (31.6 ppm Se in feed), A bisulcatus (31.7 ppm Se in feed), or sodium selenate (26.6 ppm Se in feed) with commercial hog feed. Ten control pigs were fed only commercial hog chow containing trace selenium (0.44 ppm Se). Pigs were fed for 9 weeks and necropsied when they had ataxia or paralysis. Blood was collected for hematologic and serum biochemical determinations, and samples of various tissues were collected and fixed in neutral-buffered 10% formalin for histologic evaluation or frozen for determination of selenium concentration. All forms of selenium induced clinical signs of weight and hair loss, with cracked hooves and inflamed coronary bands developing in all Na2SeO4-fed pigs and 1 A praelongus-fed pig, but not in A bisulcatus-fed pigs. Serum calcium, phosphorus, and albumin concentrations were unchanged or significantly decreased from prefeeding values in groups fed selenium. Serum aspartate transaminase (AST) activities in Astragalus species-fed groups, and amylase activities and PCV in all groups of pigs fed selenium, were increased. Serum alkaline phosphatase and creatine kinase activities were significantly increased in the A praelongus-fed pigs and significantly decreased in Na2SeO4-fed pigs. Terminal tissue and body fluid selenium concentrations were determined in all groups of pigs fed selenium and compared with values in control pigs. Urine and bile concentrations were increased by the greatest factor (40 to 100x), with tissue concentrations of selenium increased by a lesser factor (6 to 17x).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Pollen and water limitation in Astragalus scaphoides, a plant that flowers in alternate years.

Mast seeding is common in plant populations, but its causes have rarely been tested experimentally. We tested mechanisms of alternate-year flowering and fruit set in an iteroparous, bee-pollinated, herbaceous plant, Astragalus scaphoides, in semi-arid sagebrush steppe. Patterns of reproduction from 1986 to 1999 indicated that spring precipitation was a cue for synchronous flowering, and that increased pollination in high-flowering years was a fitness advantage of synchrony. We tested these patterns by adding supplemental water and pollen to plants in high- and low-flowering sites and years. Supplemental water had no effect on flowering or seed set, so water is not a proximate cue for reproduction, though it could be important over longer (>3 year) time scales. Supplemental pollination increased fruit set in low- but not high-flowering years, indicating that synchronous flowering increases pollination success. Many shorter-term studies also report increased fruit set after pollen supplementation, but not after resource addition. This pattern may reflect the fact that plants can store and reallocate resources, but not pollen, across multiple years. For animal-pollinated herbs such as these, uniting theories about pollination ecology and mast seeding may promote an understanding of the mechanisms that determine patterns of reproduction over time.

Astragalus Plant↗
PubMed2004

Use of the tobacco feedback-insensitive anthranilate synthase gene (ASA2) as a selectable marker for legume hairy root transformation.

The feedback-insensitive anthranilate synthase ( ASA2) cDNA--isolated from a 5-methyltryptophan (5MT)-resistant tobacco cell line--driven by the CaMV 35S promoter or 606 bp of the native ASA2 promoter, was introduced into the forage legume plant Astragalus sinicus or soybean ( Glycine max), using Agrobacterium rhizogenes strains DC-AR2 or K599, respectively. Hairy roots of A. sinicus transformed with 35S-ASA2 but not 606- ASA2 could be directly selected using 20-75 micro M 5MT. ASA2 mRNA was expressed in all A. sinicus lines selected with 5MT, but nptII mRNA was expressed only in some lines even though the gene was present. Free tryptophan was increased 8- to 26-fold in A. sinicus and 3- to 6-fold in soybean (selected with kanamycin). An HPLC method was used to measure anthranilate synthase (AS) activity since there was a fluorescent compound or compounds present in the soybean hairy root extracts. The transformed soybean hairy roots contained more feedback-resistant AS activity, showing that there is interaction of the tobacco ASA2 alpha-subunit with the soybean beta-subunit to form an active enzyme. Soybean hairy roots that express ASA2 also exhibit 5MT resistance. These results demonstrate that the tobacco feedback-insensitive ASA2 gene can be used as a selectable marker for transformation of the legume A. sinicus.

Anthranilate Synthase↗
PubMed1996

An analysis of genetic variation in Astragalus cremnophylax var. cremnophylax, a critically endangered plant, using AFLP markers.

A recently developed molecular technique (amplified fragment length polymorphisms, AFLP) was used for characterizing genetic heterogeneity within and among populations of a critically endangered species of plant, Astragalus cremnophylax var. cremnophylax. Using AFLP, up to 50 polymorphic genetic markers per AFLP-PCR amplification were generated, and a total of 220 variable markers overall. This information was used first to assess genetic diversity within each of the three known populations of Astragalus cremnophylax var. cremnophylax from Grand Canyon National Park in Arizona, USA: North Rim (NR; n = 970), South Rim Site 1 (SR1; n = 500), and South Rim Site 2 (SR2; n = 2). Diversity in the form of average heterozygosity [symbol: see text] H [symbol: see text] and the proportion of polymorphic genes [symbol: see text] P [symbol: see text] was greatest in the NR population ([symbol: see text] H [symbol: see text] = 0.13 and [symbol: see text] P [symbol: see text] = 0.38) and least in the SR2 population ([symbol: see text] H [symbol: see text] = 0.02 and [symbol: see text] P [symbol: see text] = 0.04). Diversity was also quite low for the SR1 population ([symbol: see text] H [symbol: see text] = 0.04 and [symbol: see text] P [symbol: see text] = 0.10). In addition, substantial genetic differentiation among populations was indicated by both phenetic (AMOVA) and genetic analyses (overall corrected FST = 0.41). This finding was corroborated by the results of several multivariate analyses which utilized the genetic data, including a UPGMA cluster analysis and a principal coordinate analysis which revealed the existence of discrete groups corresponding to the populations. Population structure was further revealed within the NR population which was known to consist of four spatially separated groups of plants. Several recommendations for the future management of the species are discussed.

Genetic Markers↗
PubMed2000

[Improved protoplast-derived plants of Astragalus adsurgens through somatic embryogenesis].

Embryogenic callus was obtained only from hypocotyl explants of Astragalus adsurgens and light inhibited the formation of embryogenic callus. A high yield (1.2 x 10(6)/g F. Wt.) of protoplasts with high viability (over 80%) could be isolated from 10-day-old embryogenic callus. Protoplasts were induced to undergo sustained division and to form cell colonies when cultured in agarose-solidified medium (KMP) containing 1/4 strength of mineral salts and supplemented with 1.5 mg/L 2, 4-D, 0.5 mg/L BA and 0.5 mol/L glucose at a plating density of 1.0 x 10(5)mL, where the plating efficinency was 16.8%. Conditioning medium significantly improved the formation of cell colonies. When protoplast-derived colonies were maintained at 4 degrees C for 2 weeks and subsequently transferred onto medium (MS) with 0.1 mg/L NAA and 1.0 mg/L BA, somatic embryogenesis occurred. Frequency of cell colonies producing somatic embryos reached 70%, and the number of somatic embryos per gram cells was over 200. Cultured on hormone-free half-strength MS medium, somatic embryos developed into healthy plantlets with normal chromosome complement.

Cells, Cultured↗
PubMed2004

Production of Se-methylselenocysteine in transgenic plants expressing selenocysteine methyltransferase.

BACKGROUND: It has become increasingly evident that dietary Se plays a significant role in reducing the incidence of lung, colorectal and prostate cancer in humans. Different forms of Se vary in their chemopreventative efficacy, with Se-methylselenocysteine being one of the most potent. Interestingly, the Se accumulating plant Astragalus bisulcatus (Two-grooved poison vetch) contains up to 0.6% of its shoot dry weight as Se-methylselenocysteine. The ability of this Se accumulator to biosynthesize Se-methylselenocysteine provides a critical metabolic shunt that prevents selenocysteine and selenomethionine from entering the protein biosynthetic machinery. Such a metabolic shunt has been proposed to be vital for Se tolerance in A. bisulcatus. Utilization of this mechanism in other plants may provide a possible avenue for the genetic engineering of Se tolerance in plants ideally suited for the phytoremediation of Se contaminated land. Here, we describe the overexpression of a selenocysteine methyltransferase from A. bisulcatus to engineer Se-methylselenocysteine metabolism in the Se non-accumulator Arabidopsis thaliana (Thale cress). RESULTS: By over producing the A. bisulcatus enzyme selenocysteine methyltransferase in A. thaliana, we have introduced a novel biosynthetic ability that allows the non-accumulator to accumulate Se-methylselenocysteine and gamma-glutamylmethylselenocysteine in shoots. The biosynthesis of Se-methylselenocysteine in A. thaliana also confers significantly increased selenite tolerance and foliar Se accumulation. CONCLUSION: These results demonstrate the feasibility of developing transgenic plant-based production of Se-methylselenocysteine, as well as bioengineering selenite resistance in plants. Selenite resistance is the first step in engineering plants that are resistant to selenate, the predominant form of Se in the environment.

Arabidopsis↗
PubMed1979

Isolation and Partial Characterization of Transfer RNAs from Astragalus bisulcatus.

A procedure has been developed for the isolation of transfer RNA from the selenium accumulator plant Astragalus bisulcatus. This material appears free of interfering phenolic compounds, has a high guanosine to cytidine ratio, shows a major and modified nucleoside composition characteristic of plant transfer RNAs, and exhibits chromatographic and electrophoretic properties similar to transfer RNAs from other well studied bacterial and plant systems. RNAs isolated from A. bisulcatus seedlings incubated in the presence of (75)Se indicate some incorporation of radioactivity into the transfer RNAs, but at extremely low levels. The transfer RNAs were active in accepting amino acids, although their over-all levels of activity appeared low when compared with those from a homologous Escherichia coli aminoacylation reaction system.

Journal Article↗
PubMed1998

Variation of selenium content in growing wild plants during vegetative period.

There is evidence that selenium (Se) is essential for humans, animals, and some species of microorganisms. This study examines the dynamics of the change of Se accumulation in some growing wild plants: Astragalus onobrychis var. Chlorocarpus (Gris.) Stoj. et Stef. (Leguminosae), Oxytropis pilosa (L.) DC., Salvia officinalis, L., and Simphytum ottomanum L. The influences of some ecological factors (Se content in soil, temperature, and rainfall) have also been surveyed. The Se content of plants from Serbia was 44.5 to 177.0 microg/kg of dry weight. Astragalus onobrychis var. Chlorocarpus (Gris.) Stoj. et Stef. (Leguminosae) accumulates the highest Se content in the blooming stage (161.3 microg/kg). All soils studied were deficient in selenium (< 250 microg/kg). We found a significant correlation between Se content in plants and in the soil (p = 0.88). Rainfall has an influence on Se content in Oxytropis, Salvia, and Simphytum, but not in Astragalus. Our results suggest that Se cannot have a similar role in all plants examined.

Environment↗
PubMed2002

[Determination of trace sulfur and mercury in the Chinese traditional medicine].

This paper reports that the sulfur compounds of traditional Chinese medicine were reduced to S2- by Auger reagent, and determined by cold atomic fluorescence. At the same time the trace mercury was determined. The conditions the for quantitative determination of Hg2+ and S2- were obtained. The linear range of the determination is 11.20-55.60 mg.mL-1, the correlation coefficient is 0.999 78. In this method, little reagent is needed, the treatment of the sample is simple, the process of determination is convenient, and the sensitivity is high.

Astragalus Plant↗
PubMed2006

[Determination of three constituents in Radix Astragali by HPLC-MS].

AIM: To determine calycosin-7-O-beta-D-glucoside, astragaloside IV and formononetin in Radix Astragali and other relative samples by HPLC-MS. METHODS: HPLC was carried out with Agilent 1100LC/MSD, equipped with Agilent Zorbax SB C18 column (250 mm x 4.6 mm ID, 5 microm) and mass spectrum detector. The mobile phase (CH3CN-H2O) was eluted in gradient mode. RESULTS: The calibration curves of calycosin-7-O-beta-D-glucoside, astragaloside IV and formononetin were linear in the range of 0.03 - 1.21 microg x mL(-1), 0.35 - 13.86 microg x mL(-1) and 0.38 - 15.22 microg x mL(-1), respectively. These recoveries of samples were from 95% to 105% with RSD less than 1.5%. CONCLUSION: The method was employed to analyse 25 samples of Radix Astragali and other relative samples, including Radix Astragali slice, Radix Astragali Preparata, Hedysarum polybotrys Hand. -Mazz, Astragalus ernestii Comb. The contents of three constituents vary greatly because of the species, place of collection and season of harvesting. This method could apply to evaluate the quality of Radix Astragali and it is simple, sensitive and reliable.

Astragalus Plant↗
PubMed2001

[Study of unified analytical method of compatibleness for traditional Chinese medicines. II. The quantitation of curve fitting].

To introduce method of compatibleness analysis for traditional Chinese medicines, we select a part of the results from the study of astragalus root(A.), Chinese angelica root(Ca.) and their complex prescription (Danggui Buxue Tang, DBT) with an analytical mode of reversed-phase HPLC-photodiode array detector as an example of the quantitation of curve fitting. A new quantitative method, the concentration variation of components as the changing of single prescription dosage in complex prescriptions is discussed. This is the second part of the method of compatibleness analysis for traditional Chinese medicines.

Angelica sinensis↗