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At least 217 records · Page 12Linked to original sources
PubMed2003

Blackgram fiber (Phaseolus mungo): mechanism of hypoglycemic action.

The effect of the administration of blackgram fiber (Phaseolus mungo) on the metabolism of carbohydrates was studied in rats fed 30% NDF (neutral detergent fiber) diet. The experimental group showed a significant increase in liver glycogen level and a significant decrease in blood glucose. Significant increases in the activities of glycogen phosphorylase, hexokinase, fructose-1, 6-diphosphatase, glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase were observed in the experimental group. The activities of phosphoglucomutase and glucose-6-phosphatase were significantly lower in rats fed the fiber diet. The study showed that blackgram fiber exhibits significant hypoglycemic action in experimental animals.

Animals↗
PubMed2005

Mating system of wild Phaseolus lunatus L. and its relationship to population size.

Using isozyme variation in a naturally pollinated seed family for 10 wild Phaseolus lunatus L. (Lima bean) populations, ranging in sizes from 10 to 60 reproductive individuals, we estimated levels of outcrossing (t) and parental inbreeding coefficient (F). We also examined the relationship between outcrossing rate and population size. Average estimates of the single-locus outcrossing rate (ts) ranged from 0.024 to 0.246 (mean=0.091+/-0.065). Estimates of the multilocus outcrossing rate (tm) ranged from 0.027 to 0.268, and averaged 0.096+/-0.071. Inbreeding coefficients based on genotypic frequencies of maternal plants were positive and significantly greater than zero (F=0.504), suggesting an excess of homozygotes in all the populations studied. There was indirect evidence of nonrandom mating for outcrosses and this was mainly attributed to self-fertilisation since the averaged difference between tm and ts, which provides a measure of biparental inbreeding, represents only 1% of the autogamy rate. No significant correlation was observed between outcrossing rate and population size. Estimates of t showed significant heterogeneity among populations and factors explaining this tendency are suggested.

Electrophoresis, Starch Gel↗
PubMed2003

Polymorphism of a complex resistance gene candidate family in wild populations of common bean (Phaseolus vulgaris) in Argentina: comparison with phenotypic resistance polymorphism.

Fifteen populations of wild bean (Phaseolus vulgaris), located in three provinces in Argentina, were analysed for their polymorphism for a complex resistance gene candidate (RGC) family clustered on the genome and for resistance phenotypes to strains of Colletotrichum lindemuthianum. Results indicate that RGC polymorphism is high. Population structure obtained for markers related to resistance was compared to population structure obtained for RAPD markers in order to infer the evolutionary forces driving polymorphism for resistance in wild populations at both molecular and phenotypic levels. Hierarchical analysis of differentiation showed that, within provinces, populations were differentiated for RAPD as well as for molecular and phenotypic markers of resistance. In contrast, provinces were differentiated only for RAPD and RGC markers and not for resistance phenotypes. The discrepancies found between diversity structures for molecular markers (RAPD and RGCs) and for resistance phenotypes suggest an effect of selection and indicate that diversity for resistance may not be driven by the same selective forces at the molecular and phenotypic levels. We further discuss whether specific selective forces are exerted on RGC markers and underline the importance of spatial scale of analysis for demonstrating an impact of selection.

Argentina↗
PubMed2005

Inheritance of a recessive transgene-associated character controlling albinism in transgenic bean (Phaseolus vulgaris L.).

We identified a transgenic line exhibiting albinism during our work to introduce genes through genetic engineering in dry bean (Phaseolus vulgaris). The transgenic mother plant (R0) presented a normal phenotype and generated albino and normal green plants in the first generation (R1). The segregation ratio of the albino character in the R1 and R2 generations fitted the expected ratio for a character controlled by a single recessive gene linked to a foreign gus gene, suggesting that albinism could be a consequence of insertional mutation caused by introduction of the exogenous gene. Analysis by electron microscope revealed that the albino cells possessed no chloroplasts and a greater number of mitochondria when compared to normal green plants. This transgenic bean line may be used in understanding the genetic control of chloroplast genesis, for acquiring additional knowledge of genomic structure or in physiological studies. This is the first described transgene-associated mutant bean plant.

Chloroplasts↗
PubMed2004

Analysis of Rhizobium etli and of its symbiosis with wild Phaseolus vulgaris supports coevolution in centers of host diversification.

Common beans (Phaseolus vulgaris) comprise three major geographic genetic pools, one in Mexico, Central America, and Colombia, another in the southern Andes, and a third in Ecuador and northern Peru. Species Rhizobium etli is the predominant rhizobia found symbiotically associated with beans in the Americas. We have found polymorphism in the common nodulation gene nodC among R. etli strains from a wide range of geographical origins, which disclosed three nodC types. The different nodC alleles in American strains show varying predominance in their regional distributions in correlation with the centers of bean genetic diversification (BD centers). By cross-inoculating wild common beans from the three BD centers with soils from Mexico, Ecuador, Bolivia, and Northwestern Argentina, the R. etli populations from nodules originated from Mexican soil again showed allele predominance that was opposite to those originated from Bolivian and Argentinean soil, whereas populations from Ecuadorian soil were intermediate. These results also indicated that the preferential nodulation of beans by geographically related R. etli lineages was independent of the nodulating environment. Coinoculation of wild common beans from each of the three BD centers with an equicellular mixture of R. etli strains representative of the Mesoamerican and southern Andean lineages revealed a host-dependent distinct competitiveness: beans from the Mesoamerican genetic pool were almost exclusively nodulated by strains from their host region, whereas nodules of beans from the southern Andes were largely occupied by the geographically cognate R. etli lineages. These results suggest coevolution in the centers of host genetic diversification.

Acyltransferases↗
PubMed2002

Differential characteristics and subcellular localization of two starch-branching enzyme isoforms encoded by a single gene in Phaseolus vulgaris L.

Starch-branching enzymes (SBE) have a dominant role for amylopectin structure as they define chain length and frequency of branch points. We have previously shown that one of the SBE isoforms of kidney bean (Phaseolus vulgaris L.), designated PvSBE2, has a molecular mass (82 kDa) significantly smaller than those reported for isologous SBEs from pea (SBEI), maize (BEIIb), and rice (RBE3). Additionally, in contrast to the dual location of the pea SBEI in both the soluble and starch granule fractions, PvSBE2 was found only in the soluble fraction during seed development. Analysis of a pvsbe2 cDNA suggested that PvSBE2 is generated from a larger precursor with a putative plastid targeting sequence of 156 residues. Here we describe the occurrence of a larger 100-kDa form (LF-PvSBE2) of PvSBE2 found both in the soluble and starch granule fractions of the developing seeds. The determined N-terminal sequence, VKSSHDSD, of LF-PvSBE2 corresponded to a peptide sequence located 111 amino acids upstream from the N terminus of purified PvSBE2, suggesting that LF-PvSBE2 and PvSBE2 are products of the same gene. Analysis of the products by 5'-RACE (rapid amplification of cDNA ends) and reverse transcription PCR indicated that the two transcripts for pre-LF-PvSBE2 and pre-PvSBE2 are generated by alternative splicing. Recombinant LF-PvSBE2 (rLF-PvSBE2) was purified from Escherichia coli and the kinetic properties were compared with those of recombinant PvSBE2 (rPvSBE2). rLF-PvSBE2 had much higher affinity for amylopectin (K(m) = 4.4 mg/ml) than rPvSBE2 (18.4 mg/ml), whereas the V(max) of rLF-PvSBE2 (135 units/mg) for this substrate was much lower than that of rPvSBE2 (561 units/mg). These results suggest that the N-terminal extension of LF-PvSBE2 plays a critical role for localization in starch granules by altering its enzymatic properties.

1,4-alpha-Glucan Branching Enzyme↗
PubMed2002

The high specificities of Phaseolus vulgaris erythro- and leukoagglutinating lectins for bisecting GlcNAc or beta 1-6-linked branch structures, respectively, are attributable to loop B.

Despite very similar tertiary structures based upon a common framework, legume lectins exhibit an amazing variety of sugar binding specificities. While most of these lectins recognize rather discrete sugar linkages, Phaseolus vulgaris erythroagglutinating and leukoagglutinating lectins (E(4)- and L(4)-PHA) are unique in recognizing larger structures. E(4)- and L(4)-PHA are known to recognize complex type N-glycans containing bisecting GlcNAc or a beta1,6-linked branch, respectively. However, the detailed mechanisms of molecular recognition are poorly understood. In order to dissect the contributions of different portions of each lectin, we carried out region-swapping mutagenesis between E(4)- and L(4)-PHA. We prepared six chimeric lectins by exchanging different combinations of loop B and the central portion of loop C, two of four loops thought to be important for the recognition of monosaccharides (Sharma, V., and Surolia, A. (1997) J. Mol. Biol. 267, 433-445). The chimeric lectins' sugar binding activities were evaluated quantitatively by surface plasmon resonance. These comparisons indicate that the high specificities of E(4)- and L(4)-PHA toward bisecting GlcNAc and beta1,6-linked branch structures are almost solely attributable to loop B. The contribution of the central portion of loop C to the recognition of those structural motifs was found to be negligible. Instead, it modulates affinity toward LacNAc residues present at the nonreducing terminus. Moreover, some of the chimeric lectins prepared in this study showed even higher specificities/affinities than native E(4)- and L(4)-PHA toward complex sugar chains containing either a bisecting GlcNAc residue or a beta1,6-linked branch.

Acetylglucosamine↗
PubMed2004

Root uptake, transport, and metabolism of externally applied glutathione in Phaseolus vulgaris seedlings.

The most abundant thiol in beans (Phaseolus vulgaris L. cv. Saxa) is the tripeptide homoglutathione (hGSH) rather than glutathione (GSH). At the whole-plant level the GSH content is less than 0.5% of the hGSH content. In the present study GSH was supplied to the roots of bean seedlings to test whether GSH can be taken up by roots and transported to the shoot. Therefore, 12-day-old plants were exposed to 1 mmol/L GSH for 4, 8 and 24 h prior to harvest. In response to this GSH exposure, elevated GSH contents were found in all tissues. After 4 h the GSH content increased in the roots from 1 +/- 1 to 22 +/- 2 nmol GSH g(-1) fresh weight (FW), in the leaves from 2 +/- 1 to 9 +/- 4 nmol GSH g(-1) FW, and in the apex from 30 +/- 5 to 75 +/- 4 nmol GSH g(-1) FW. These data indicate that GSH is taken up by bean roots and is transported to above above-ground parts of the plants. Roots exposed to GSH for 24 h contained 2-fold higher cysteine (Cys) and hGSH contents than the controls. Apparently, GSH taken up by the roots is not only loaded into the xylem but also partially degraded and used for hGSH synthesis.

Biological Transport, Active↗
PubMed2003

Crystallochemical characterization of calcium oxalate crystals isolated from seed coats of Phaseolus vulgaris and leaves of Vitis vinifera.

Calcium oxalate crystals are a major biomineralization product in higher plants. Their biological function and use are not well understood. In this work, we focus on the isolation and crystallochemical characterization of calcium oxalate crystals from seed coats of Phaseolus vulgaris (prisms) and leaves of Vitis vinifera (raphides and druses) using ultrastructural methods. A proposal based on crystal growth theory was used for explaining the existence of different morphologies shown by these crystals grown inside specialized cells in plants.

Calcium Oxalate↗
PubMed2004

Different classes of proteases are involved in the response to drought of Phaseolus vulgaris L. cultivars differing in sensitivity.

Protein breakdown and recycling, which depend on the levels of proteolytic enzymes, are an essential part of the plant response to environmental stress. In order to study changes in the activity of proteases in Phaseolus vulgaris L. subjected to water deficit, three cultivars of European origin that exhibit different degrees of sensitivity to drought were chosen on the basis of changes in water potential, psiw, water and protein contents of leaves during progressive water deficit, and loss of membrane integrity after osmotic stress. Twenty-day-old plants were subjected to water deficit by withholding irrigation. Specific enzyme activities in leaf extracts were determined for plants under different degrees of drought stress using different substrates and protease inhibitors. Proteolytic activities were partially characterized by gel exclusion chromatography. Activities of two of the three identified serine proteinases changed under water deficit. The activity of the one with apparent molecular mass of approximately 65 kDa was observed to increase progressively with increasing withdrawal of water in the more sensitive cultivars, but to decrease in the more resistant cultivar. The same activity was elevated in senescent leaves. Under conditions of severe water deficit, the most sensitive cultivar exhibited a marked increase in the activity of two different aminopeptidases, while the more resistant cultivar showed a significant decrease in the activity of these aminopeptidases. These results point to complex and probably specific roles for different proteases in the plant response to drought.

Aminopeptidases↗
PubMed2003

Molecular composition and surface properties of storage lipid particles in wax bean (Phaseolus vulgaris).

Lipid particles have been isolated from seeds of wax bean (Phaseolus vulgaris), a species in which starch and protein rather than lipid are the major seed storage reserves. These lipid particles resemble oil bodies present in oil-rich seeds in that > 90% of their lipid is triacylglycerol. Moreover, this triacylglycerol is rapidly metabolized during seed germination indicating that it is a storage reserve. The phospholipid surfaces of oil bodies are known to be completely coated with oleosin which prevents their coalescence, particularly during desiccation of the developing seed. This would appear to be necessary since lipid is the major storage reserve in oil seeds, and there are very few alternate types of storage particles in the cytoplasm of oil seed endosperm to provide a buffer against coalescence of oil bodies by isolating them from one another. The present study indicates that the surfaces of lipid particles from wax bean are not completely coated with oleosin and feature regions of naked phospholipid. This finding has been interpreted as reflecting the fact that lipid particles in wax been seeds are less prone to coalescence than oil bodies of oil-rich seeds. This arises because the individual lipid particles are interspersed in situ among highly abundant protein bodies and starch grains and hence less likely to come in contact with one another, even during desiccation of the developing seed.

Amino Acid Sequence↗
PubMed2003

Relating foliar dehydration tolerance of mycorrhizal Phaseolus vulgaris to soil and root colonization by hyphae.

Mycorrhizal symbiosis can modify plant response to drying soil, but little is known about the relative contribution of soil vs. root hyphal colonization to drought resistance of mycorrhizal plants. Foliar dehydration tolerance, characterized as leaf and soil water potential at the end of a lethal drying episode, was measured in bean plants (Phaseolus vulgaris) colonized by Glomus intraradices or by a mix of arbuscular mycorrhizal fungi collected from a semi-arid grassland. Path analysis modeling was used to evaluate how colonization rates and other variables affected these lethal values. Of several plant and soil characteristics tested, variation in dehydration tolerance was best explained by soil hyphal density. Soil hyphal colonization had larger direct and total effects on both lethal leaf water potential and soil water potential than did root hyphal colonization, root density, soil aggregation, soil glomalin concentration, leaf phosphorus concentration or leaf osmotic potential. Plants colonized by the semi-arid mix of mycorrhizal fungi had lower lethal leaf water potential and soil water potential than plants colonized by G. intraradices. Our findings support the assertion that external, soil hyphae may play an important role in mycorrhizal influence on the water relations of host plants.

Disasters↗
PubMed2004

Salicylic acid-, but not cytokinin-induced, resistance to WClMV is associated with increased expression of SA-dependent resistance genes in Phaseolus vulgaris.

Two-week-old Phaseolus vulgaris plants, wick-fed with 1 mmol/L salicylic acid (SA) or 50 nmol/L dihydrozeatin (DHZ), showed partial inhibition of the accumulation of white clover mosaic virus (WClMV) in infected primary leaves. This inhibition was measured as a decrease in the accumulation of both viral mRNA and viral coat protein, especially at the early stages of infection. Salicylic acid treatment resulted in moderately increased expression of phenylalanine ammonia lyase (PAL), NPR1, PR1 and HSP70 genes that participate in resistance to pathogens in plants. In contrast, DHZ treatments did not induce significant changes in expression of these genes. The expression of the P. vulgaris alternative oxidase (AOX) gene homolog, an enzyme implicated in plant resistance to viruses, showed low constitutive expression during the first 11 days post-infection and was not affected by either SA or DHZ. It appears that, while SA induced the NPR1-PR1 pathogen defense pathway genes, both SA and DHZ may use a different pathway to induce resistance to WClMV infection in P. vulgaris plants.

Base Sequence↗
PubMed2004

Hypoglycaemic and anorexigenic activities of an alpha-amylase inhibitor from white kidney beans (Phaseolus vulgaris) in Wistar rats.

An inhibitor of alpha-amylase was isolated and purified from an extract of white kidney beans (Phaseolus vulgaris). The acute oral administration of the inhibitor (50 mg/kg body weight) to adult Wistar rats together with a starch load (2 g/kg body weight suspended in NaCl (9 g/l)) reduced the increase in glycaemia over the basal value (NaCl, 222 (SEM 49); inhibitor, 145 (SEM 16) mmol/l x 180 min; P<0.05) without modifying the insulin response. On administering the inhibitor orally (50 mg/kg body weight dissolved in NaCl (9 g/l)) for 21 d to rats fed on a standard diet, a decline was observed in the glycaemia values on day 0 (NaCl, 5.53 (SEM 0.12); inhibitor, 5.25 (SEM 0.16) mmol/l) relative to those obtained on days 10 (NaCl, 5.00 (SEM 0.14); inhibitor, 4.60 (SEM 0.08) mmol/l; P<0.05) and 21 (NaCl, 5.22 (SEM 0.22); inhibitor, 4.50 (SEM 0.12) mmol/l; P<0.01) of treatment, without modifying the plasma concentration of insulin. There was found to be a significant anorexigenic action of the inhibitor; there was reduced food intake (NaCl, 23.07 (SEM 0.31); inhibitor, 19.50 (SEM 0.49) g/d; P<0.01), a reduced weight gain (NaCl, 52 (SEM 3); inhibitor, -1.33 (SEM 8.9) g/21 d; P<0.01), as well as changes in the activity of some intestinal enzymes such as maltase (NaCl, 87 (SEM 7); inhibitor, 127 (SEM 11) U/g proteins; P<0.05). The present study has shown, for the first time, that the prolonged administration of an alpha-amylase inhibitor reduces blood glucose levels and body-weight gain in Wistar rats.

Administration, Oral↗
PubMed2002

Methylarsonic and dimethylarsinic acids toxicity and total arsenic accumulation in edible bush beans, Phaseolus vulgaris.

The main objective was to evaluate whether arsenic accumulated in the edible pods and seeds of Phaseolus vulgaris, cv. F15 above the Spanish maximum recommended concentration for food crops, 1 mg kg(-1) on a fresh weight basis. Only organic arsenicals, methylarsonic and dimethylarsinic acids were used because they were: (1) the only arsenic species allowed for agricultural applications and (2) more mobile than inorganic species. Selection of French beans, a sensitive plant to arsenic, was based on the fact that arsenic-upward translocation is higher in sensitive than in tolerant plants. A 2 x 3 factorial experiment was conducted with two organic arsenic species (methylarsonic acid, dimethylarsinic acid) and three arsenic concentrations (0.2, 0.5, 1.0 mg l(-1)). Experimental results showed that the low bean plant tolerance to arsenic was possibly due to the high arsenic-upward transport to shoots, which could result in profound negative metabolic consequences. Even under extreme adverse conditions, arsenic residues in edible beans were below the maximum statutory limit set by the Spanish legislation. It is concluded that the major drawback of organic arsenical herbicides is that of decreased productivity rather than high arsenic intake by consumers of edible products from sensitive plant species.

Arsenicals↗
PubMed2005

Antinutritional factors and in vitro protein digestibility of improved haricot bean (Phaseolus vulgaris L.) varieties grown in Ethiopia.

The antinutrient (raffinose oligosaccharides, tannins, phytic acid and trypsin inhibitors) composition and in vitro protein digestibility of eight improved varieties of Phaseolus vulgaris grown in Ethiopia were determined. Stachyose was the predominant alpha-galactosides in all haricot bean samples. Raffinose was also present in significant quantities but verbascose, glucose and fructose were not detected at all in the samples. The concentrations observed for the protein digestibility and antinutritional factors, varied significantly (P<0.05) between varieties investigated in this study. Mean values for protein digestibility ranged from 80.66% (in Roba variety) to 65.64% (in Beshbesh variety). Mean values for raffinose, stachyose, sucrose, trypsin inhibitors, tannins and phytic acid were 3.14 mg/g, 14.86 mg/g, 24.22 mg/g, 20.68 TUIx10(3)/g, 17.44 mg, catechin equivalents/g and 20.54 mg/g respectively. Statistical analyses of data revealed that antinutritional factors and protein digestibility were influenced by variety (genotype). Relationships between antinutritional factors and protein digestibility were also observed. The possibility of selecting varieties to be used for large-scale cultivation in Ethiopia on the basis of these data is discussed. Among the improved varieties studied, Roba, Redwolaita, Mexican and Awash were found to be the best food and export type of haricot beans in the Ethiopian context, because of their higher protein digestibility, lower antinutrtional factors and other beneficial nutritional parameters. Roba variety can be used by local food processors for the production of value-added bean-based products especially to combat the problem of protein energy malnutrition and related diseases which are very common in developing countries.

Dietary Proteins↗
PubMedDate not supplied

Toxicity studies of Blockal, a dietary supplement containing Phase 2 Starch Neutralizer (Phase 2), a standardized extract of the common white kidney bean (Phaseolus vulgaris).

The number of available dietary supplements containing "starch blockers" intended for weight loss has risen dramatically in recent years. These supplements are believed to reduce carbohydrate-derived calories by interfering with alpha-amylase, the digestive enzyme responsible for conversion of complex carbohydrates to simple absorbable sugars. The present paper reports the findings of single- and multiple-dose (4-week) oral toxicity studies in rats of the marketed dietary supplement Blockal. Blockal contains as its main ingredient Phase 2 Starch Neutralizer (Phase 2 or Phaseolamin 2250), a standardized extract derived from the common white kidney bean (Phaseolus vulgaris) that has been shown to have alpha-amylase-inhibiting activity. The Blockal acute oral LD50 exceeded the highest dose tested (3 g/kg body weight [bw]), which provided a single dose of 1668 mg/kg bw of Phase 2 white kidney bean extract. The no-observed-effect level (NOEL) seen in the 4-week study was equivalent to the highest Blockal dose tested (2 g/kg bw/day), which provided 1112 mg/kg/day of Phase 2 white kidney bean extract. The results of these studies support and are consistent with the safety of the marketed dietary supplement Blockal, and indirectly, the safety of its main ingredient, Phase 2 Starch Neutralizer (Phase 2 or Phaseolamin 2250), a standardized extract derived from the common white kidney bean.

Animals↗
PubMed2001

Total arsenic accumulation in edible pods and seeds of Phaseolus vulgaris.

The main objective of this study was to evaluate whether arsenic accumulated in the edible pods and seeds of Phaseolus vulgaris, cv. Helda, above the Spanish maximum recommended concentration for food crops, 1 mg kg(-1) on a fresh weight basis. Only organic arsenicals were used because they are: a) the only arsenic species allowed for agricultural applications and b) more mobile than inorganic species. Selection of French beans, a sensitive plant to arsenic, was based on the fact that arsenic upward translocation is higher in sensitive than in tolerant plants. A 2 x 3 factorial experiment was conducted with two organic arsenic species: methylarsonic acid (MAA) or dimethylarsinic acid (DMAA) and three arsenic concentrations: 0.2, 0.5, or 1.0 mg L(-1). Arsenic phytotoxicity was primarily determined by soluble arsenic concentration. Experimental results showed that the low bean plant tolerance to arsenic is possibly due to the high arsenic upward transport to shoots, which could result in profound negative metabolic consequences. Even under extremely adverse conditions, arsenic residues in edible beans were below the maximum statutory limit set by the Spanish legislation. It can be concluded that the major danger of organic arsenical herbicides is that of decreased productivity rather than high arsenic uptake by consumers.

Animals↗