Characterization of polyphenolics in the seed coat of Black Jamapa bean (Phaseolus vulgaris L.)

The common bean contains phytochemicals, including phenolic compounds, which can provide health benefits to the consumer. Our objective was to characterize the polyphenolic compounds present in the seed coat of Black Jamapa bean and to test fractionation methods that permit the recovery of polyphenolics in their naturally occurring forms. A 100% methanol extract from seed coats was subjected to different chromatographic fractionation methods. Analysis by HPLC-MS revealed that a better separation of phytochemicals was achieved using direct silica gel fractionation, which allowed more accurate identification of compounds, especially of the flavonols. Anthocyanins, flavanol monomers, and heterogeneous flavanol oligomers up to hexamers were detected. To our knowledge, this is the first time that myricetin glycoside and proanthocyanidin oligomers containing (epi)-gallocatechin have been reported in the black bean. The fractionation methods used in this study produced large quantities of natural mixtures of flavonoids suitable for testing bioactivity and phytochemical interactions.     

Diversity of common bean (Phaseolus vulgaris L.) germplasm from Portugal

Common bean (Phaseolus vulgarisL.) is a traditional crop in Portugal, where farmers growvarieties selected and maintained by themselves. A collection of 88landraces of common bean was evaluated for 17 quantitative andqualitative traits and the biochemical marker phaseolin to displaythe degree of variation of this germplasm. Agronomic data weresubjected to cluster analysis and several groups were identified,with three groups clustering most of the landraces. Regardingphaseolin variation the C and T banding patterns are the mostfrequent ones, so the origin of the Portuguese beans is thus probablythe Andean region of South America. These results give informationabout the origin, diversity and breeding value of the Portuguesegermplasm, that could be useful to widen the genetic base ofcurrently cultivated bean varieties in Europe.     

Polyphenol oxidase activity and differential accumulation of polyphenolics in seed coats of pinto bean (Phaseolus vulgaris L.) characterize postharvest color changes

Postharvest darkening of pinto bean (Phaseolus vulgaris L.) was evaluated in a population of recombinant inbred lines derived from a cross between CDC Pintium (a regular-darkening line) and 1533-15 (a slow-darkening line). Flavonoid metabolite concentrations, polyphenol oxidase activity, lignin concentration, and seed coat anatomy characteristics were assessed for cosegregation with the darkening phenotype. Significantly lower kaempferol concentrations (p = 0.00001) together with differences in polyphenol oxidase activity (p = 0.0045) were two of the key findings associated with these recombinant inbred lines. In addition, two different assays (thioglycolic acid and Klason lignin) to quantify lignin together with an assessment of extractable condensed tannin were used to estimate the contribution of these polymers to changes in the seed coat tissue. This is the first report of precise biochemical characterization of polyphenolics that associate with postharvest darkening in legumes.     

Anthocyanin profile of Korean cultivated kidney bean (Phaseolus vulgaris L.)

This investigation was conducted to determine the structures and amounts of anthocyanins obtained from seed coats of kidney bean (Phaseolus vulgaris L.) cultivated in Korea. Anthocyanins in the seed coat of kidney bean were extracted with 1% HCl/20% CH(3)OH, and the crude anthocyanin extracts were purified by semipreparative HPLC. Five major anthocyanins were isolated, and their chemical structures were identified by spectroscopic methods (UV-vis, LC/ES-MS, and 1H and 13C NMR). The structures of these five anthocyanins were elucidated as cyanidin 3,5-diglucoside, delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, and pelargonidin 3-glucoside. Using RP-HPLC with photodiode array detection, each of the five anthocyanins was separated within 12 min by using a gradient elution. It was proved that the application of RP-HPLC could be an excellent method for determining the composition and contents of anthocyanins in kidney bean. The preponderance of pelargonidin 3-glucoside and delphinidin 3-glucoside are observed in red and black kidney beans, respectively. However, in this study, it is reported for the first time that the contents and composition of anthocyanins in speckled seed depend on the classes of speckle color. The contents of cyanidin 3,5-diglucoside, delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, pelargonidin 3-glucoside, and total anthocyanins in seed coats of 16 kidney beans cultivated in Korea were in the ranges of 0-0.04, 0-2.61, 0-0.12, 0-0.17, 0-0.59 and 0-2.78 mg/g of dried seed coats, respectively.     

Antioxidant activity in common beans (Phaseolus vulgaris L.)

Beans were pearled to evaluate the feasibility of increasing antioxidant activity and phenolic antioxidants. Phenolics were concentrated mostly in the hull fraction at about 56 mg of catechin equivalents per gram of sample. The methanolic extracts of the pearled bean samples were screened for antioxidant potential using the beta-carotene-linoleate and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) in vitro model systems. The pearled material, also referred to as milled samples, exhibited antioxidant activity that correlated with phenolic content and inhibited DPPH significantly in a dose-dependent manner. Phenolics and antioxidant activities were also examined in chromatographic fractions of methanolic extracts of manually obtained hulls that represented a model used previously to ascertain antimutagenic activity. Fractions extracted with ethyl acetate/acetone and acetone displayed antioxidant activity, which implies potent free radical scavenging activity with antimutagenic activity.     

Iron and zinc absorption from two bean (Phaseolus vulgaris L.) genotypes in young women

Extrinsic and intrinsic iron and zinc labels were used to test iron and zinc absorption from two bean (Phaseolus vulgaris) genotypes, containing normal (common beans, CB) or higher (HFeZnB) iron and zinc concentrations, fed in single meals to young women with low iron reserves. The women were divided into two groups, with one receiving a CB test meal (n = 12) and the other, an HFeZnB test meal (n = 11). The beans were intrinsically labeled hydroponically with (55)Fe (CB and HFeZnB) and with (70)Zn (HFeZnB). Concentrations of zinc and iron were 98 and 65% higher, respectively, in HFeZnB as compared to CB, but phytic acid contents were similar. Extrinsic labels were (59)Fe (CB and HFeZnB), (67)Zn (CB), and (68)Zn (HFeZnB). Iron and zinc percent absorption levels were calculated from radio-iron activity in red blood cells and from urinary excretion of zinc isotopes. Intrinsic and extrinsic iron absorption measures were highly correlated (R (2) = 0.986) (average extrinsic/intrinsic ratio was 1.00). Iron absorption was low (geometric mean < 2%) in both bean types, and total iron absorbed was not different between types. Intrinsic zinc absorption from the HFeZn beans was higher than extrinsic absorption (15.2% vs 13.4%, p < 0.05) (average extrinsic/intrinsic was 0.90). The correlation between intrinsic and extrinsic zinc measures was not as high as that for iron (R (2) = 0.719). Percent zinc absorption levels were similar in both bean types, but total extrinsic zinc absorbed was 90% higher (p < 0.05) from the HFeZnB meal. Thus, the less expensive and time-consuming extrinsic labeling may be used to screen various varieties of beans for iron bioavailability in humans, but it underestimates zinc absorption by approximately 10%. Selective breeding for high-zinc bean genotypes may improve zinc status. However, high-iron genotypes appear to have little effect on iron status when fed alone in single meals to women with low iron reserves.     

Breeding for bean fly resistance in common bean (Phaseolus vulgaris L.): a review

The bean fly (Ophiomya spp) is the most important yield limiting insect pest of common bean in Africa. The insect pest can cause complete crop loss affecting bean production and productivity under epidemic conditions. Effective control of bean fly is essential for sustainable bean production Africa. The overall progress, opportunities and challenges of the bean fly control strategies. The biology and ecology of bean fly and the economic importance of the insect pest is presented as well as the existing controlling strategies, with an emphasis on the breeding on breeding strategies used, research progress achieved challenges and opportunities. In conclusion, significant research progress have been made in breeding for bean fly resistance evident by identification of breeding lines, understanding resistance mechanism and development of breeding strategies. However, there is a need for further research to validate the available information and also explore new breeding methods such molecular breeding which has not been explored at present. Such studies will accelerate breeding for bean fly resistance.     

Effect of location on dwarf French bean (Phaseolus vulgaris L.) seed production and seedling vigour

ABSTRACT

This study examined if dwarf French bean (Phaseolus vulgaris L.) grown at northern latitudes develop seeds with superior yielding potential compared with plants grown at more southern latitudes. Two lines (BND3085 and BND3106) were grown at four sites across latitudes ranging from 52°N to 3°S. BND3085 and BND3106 seeds from Saskatoon grown plants (52°N) had the least damaged seed coats but the highest degree of electrolyte leakage from the seed and the lowest maximum germination rates. The Saskatoon (BND3085 and BND3106) and Nunhem (BND3106) seed lots had the lowest maximum germination rates when germinated at 28°C, 12°C, or when exposed to saline (100?mM NaCl) conditions. Saskatoon BND3085 seed produced plants with the lowest aboveground vegetative and total seed dry matter as well as the lowest pod number per plant. In contrast, plants grown from Saskatoon BND3106 seed produced 1.5-fold more total pods, 1.3-fold more total pods and 1.4-fold higher seed dry matter per plant as compared to plants grown from the Nunhem (51°N) or Arusha seed sources. This resulted in a 2.4–4.5% higher harvest index. These results suggest cultivar-specific dwarf French bean seed propagation at more northern sites may increase the productivity of the resulting crop.     

Biotransformation of common bean (Phaseolus vulgaris L.) flavonoid glycosides by bifidobacterium species from human intestinal origin

Bifidobacteria strains from human origin were screened for the specific activity (beta-glucosidase activity) involved in the metabolism of dietary flavonoids. Five strains with high beta-glucosidase activity were selected for further metabolism analyses (high-performance liquid chromatography separations) of flavonoid glycosides occurring in Phaseolus vulgaris L. (common bean) seeds and seedlings. All selected strains were found to be active in the conversion of kaempferol 3-O-glucoside, daidzin, genistin, and glycitin into their aglyconic forms. No metabolites were detected after the fermentation tests with the diglucosidic compound kaempferol 3-O-xylosylglucoside. In addition, to verify the effective bioavailability of flavonoid aglycones, the degradation rates of daidzein, genistein, glycitein, and kaempferol, following incubation with selected strains, were monitored. The results showed that the five selected strains of bifidobacteria, being active in the biotranformation of flavonoid glycosides occurring in common bean seeds and seedlings, could be considered as probiotic dietary adjuncts to improve the nutritional and health properties of flavonoid-based products, comprising hypothetical common bean food derivatives.     

Genetic diversity and population structure of a common bean (Phaseolus vulgaris L.) collection from Calabria (Italy)

Eighty-seven Phaseolus vulgaris landraces, still cultivated in Calabria (Italy), were investigated in order to study the patterns of common bean genetic diversity in this region, to better understand the evolutionary development of beans in Europe and to properly manage these genetic resources. Four American accessions and five Italian varieties were also included. Different markers, such as 12 microsatellites, seed traits, phaseolins and 100-seed weight were combined with different statistical approaches. For each microsatellite, expected (H _e ) and observed (H _o ) heterozygosities, polymorphism information content (PIC), probability of identity (PI) and homozygosity were calculated. Furthermore, in Calabrian group of bean landraces, total (N _a ) and private (N _pa ) number of alleles, observed (H _o ), expected heterozygosities (H _e ) and allelic richness (AR) were calculated. Genetic distances among landraces were estimated using Nei’s coefficient and a cluster analysis using the UPGMA algorithm was performed. The results clearly indicated that: (1) Calabrian germplasm showed a high level of diversity (H _e  = 0.595); (2) Mesoamerican and Andean gene pools were clearly distinguished in Calabrian germplasm, with the Andean gene pool predominating (83 %); (3) Calabrian landraces were largely hybridized within and between the gene pools. A model-based approach, using the STRUCTURE software, was adopted. Six groups, including 4 of Andean origin and one of Mesoamerican origin were identified. Even more interesting, a small group (8 %) showed a distinct genetic structure, in which interspecific hybridizations with runner bean (Phaseolus coccineus L.) could have occurred. Nevertheless, a relatively high proportion of Calabrian bean landraces (12.6 %) was derived from intra and interspecific hybridizations.     

Effect of exudate released from seeds and seedling roots of common bean (Phaseolus vulgaris L.) on proliferation of Rhizobium sp. (Phaseolus)

Effects of seed and root exudates obtained from common bean on the proliferation of Rhizobium sp. (Phaseolus) were examined in a combination of three plant cultivars with three Rhizobium strains. In the first experiment, seed or root exudate was mixed with an Andosol soil extract, and bacterial proliferation in the mixture was traced. Seed exudate was prepared from hydroponic solution used in seed imbibition for 24 h, and a series of root exudates was prepared from a hydroponic solution collected every 24 h from the initiation of rooting up to 96 h after rooting. Regardless of the common bean cultivars and Rhizobium strains used, Rhizobium population markedly increased of the 24 h of culture in the mixture containing seed exudates, whereas a negligible increase was detected in the mixture with root exudates. The mixture containing root exudates collected within a period of 72–96 h after initial rooting (96–120 h after seed imbibition) exerted an inhibitory effect on Rhizobium proliferation. The seed exudates contained large amounts of sugars, amino acids, nitrogen, phosphorus, potassium, and magnesium compared to any root exudates. In the second experiment, Rhizobium was inoculated directly to common bean seeds sowed in a vermiculite bed which was sterilized and moistened with a plant nutrient solution. Compared with the control (without seed), a remarkable increase in the number of bacterial cells was observed in all the combinations of plant cultivars and Rhizobium strains 24 h after sowing. These results reveal that seed exudates of common bean have a substantial potential to promote Rhizobium proliferation, and that root exudates in a particular period of culture contain some inhibitory factors.     

Phytic acid, phytase, minerals, and antioxidant activity in Canadian dry bean ( Phaseolus vulgaris L.) cultivars

Ten bean cultivars grown in southern Manitoba in 2006 were evaluated for variability in phytate, phenolic, and mineral contents, phytase activity, and antioxidant properties to elucidate the relationship of these components. Phytic acid content and phytase activity varied significantly among cultivars and market classes, ranging from 16.7 to 25.1 g/kg and from 224 to 361 phytase activity unit/kg of sample, respectively. The bean cultivars with total phenolic content ranging from 2.2 to 5.6 g of catechin equiv/kg of sample exhibited significant variation in antioxidant capacity [1.6-11.2 microM Trolox equiv (TE)/g of dry matter] and peroxyl radical scavenging activity (72-158 microM TE/g) using photochemiluminescence and fluorescence assays, respectively. Multivariate data analysis performed on 22 components analyzed in this study using principal component analysis and cluster methods demonstrate that differences in phytase, antioxidant activity, mineral contents, and bioavailability are much larger within market class than among bean cultivars.     

Polyphenols and antioxidant capacity of seed coat and cotyledon from Brazilian and Peruvian bean cultivars (Phaseolus vulgaris L.)

Seed coats and cotyledons from 25 Brazilian and 3 Peruvian bean cultivars were investigated in relation to their phenolic profiles and antioxidant capacity. Condensed tannins, anthocyanins, and flavonols such as kaempferol and quercetin glycosides were mostly found in seed coats. Cotyledons were rich in phenolic acids, such as ferulic, sinapic, chlorogenic, and other hydroxycinnamic acids. In general, the seed coat color pattern and the type of cultivar showed an important influence on the variability of phenolic profiles and levels, respectively. Total phenolics and antioxidant capacity assessed by the DPPH method were higher in seed coats than in cotyledons. The antioxidant capacity had a significant correlation with condensed tannins for all samples and with total anthocyanins in black and red seed coats, whereas in cotyledons, it was more related to the total phenolic content.     

Biodiversity of common bean (Phaseolus vulgaris L.) in Honduras, evidenced by morphological characterization

This paper describes findings in the characterization of 300 accessions in a collection of common beans (Phaseolus vulgaris L.) in Honduras. The plant material was collected from 1990 to 1994 (4 years before the damaging Mitch Hurricane) covering most of the Departments of the country and kept at the Escuela Agrícola Panamericana Zamorano. Thirty-two morpho-agronomical characters were evaluated and the results were grouped by classes. The studied accessions showed a marked diversity with high predominance of red and small seeds. The accessions with purple flowers had black seeds and originate mainly from the western area of the country where this type of seed is preferred. Principal Component Analysis shows that clearly defined groups do not exist. The conservation of this diversity is recommended for future propagation, breeding and the investigation of the genetic relationships and other studies.     

Genetic selection for enhanced bioavailable levels of iron in bean (Phaseolus vulgaris L.) seeds

The bioavailability of Fe from 24 select genotypes of bean (Phaseolus vulgaris L.) seeds containing a range of concentrations of Fe, myo-inositol pentaphosphate plus phytic acid (IP5+IP6), and tannins was studied using a rat model. Bean accessions, selected from field trials for their variations in Fe, phytate, and tannin seed concentrations, were grown in a greenhouse in nutrient solutions radiolabeled with (59)Fe. Mature seeds were autoclaved and lyophilized. Test meals (containing 1 g of dried bean, 0.5 g of sucrose, and 1 g of basal Fe-deficient diet) were fed to marginally Fe-depleted weanling rats over a 3-h period; rats were radioassayed in a gamma-spectrometer immediately after feeding and daily thereafter for the next 10 d. Radioiron retention data were used to calculate percent Fe absorption (i.e., Fe bioavailability) from the meals. Seed Fe concentrations ranged from 52 to 157 microg g(-)(1) dry weight. There was a tendency to also select for higher Zn concentrations in the beans when selecting for high Fe concentrations. The Fe bioavailability to rats from test meals depended on the genotype and varied from 53% to 76% of the total Fe. Bean genotypes with higher seed Fe concentrations resulted in increased amounts of bioavailable Fe to rats. There was no significant correlation between the Fe concentration in different bean genotypes and Fe bioavailability to rats attributable to variations in IP5+IP6 or tannins, even though these antinutrients varied widely (i.e., from 19.6 to 29.2 micromol of IP5+IP6 g(-)(1) and from 0.35 to 2.65 mg of tannins g(-)(1)) in the test meals. Other unknown seed factors (i.e., antinutrients or promoter substances) may be contributing factors affecting Fe bioavailability from bean seeds.     

Application and fate of Cyromazine in a closed-cycle hydroponic cultivation of bean (Phaseolus vulgaris L.)

The fate of cyromazine applied via the nutrient solution (20, 40, and 60 mg of active ingredient per plant) in a closed-cycle soilless cultivation of bean with zero discharge of effluents was traced in both the recycled drainage solution and the plant tissues for 99 days. The insecticide was applied once, 15 days after planting (16 days prior to the first harvest). In addition to cyromazine, the residues of melamine, its metabolite, in the drainage solution and plant tissues were also regularly determined during the 99 days. The two higher application doses induced toxicity symptoms on the leaves of the bean plant. The maximum cyromazine levels were measured 8 days after application in the drainage solution (17-46 mg l(-1)), 16 days in the roots (1.1-2.4 mg kg(-1) fresh weight [f. wt.]) and the vegetative shoot (4.5-9.5 mg kg(-1) f. wt.), and 24 days after application in the pods (2.6-4.1 mg kg(-1) f. wt.). However, the cyromazine residues in pods were clearly below the maximum acceptable levels for bean. The half-life of cyromazine in the drainage solution ranged from 16 to 19 days for the three doses. The melamine residues in the drainage solution and in the roots reached a concentration peak 16 days after cyromazine application, whereas in the vegetative shoot and the pods they were constantly increasing over the 99 days after application. Nevertheless, the melamine residues were constantly much lower than those of cyromazine, although on the last sampling day (99) they tended toward convergence. Cyromazine proved to be highly persistent, as indicated by the remarkably high residues measured in both the drainage solution and the plant tissues, even 99 days after application. Nevertheless, the application of cyromazine via the nutrient solution to beans grown in closed-cycle hydroponic systems at doses not exceeding 20 mg per plant seems to be safe with respect to both phytotoxicity and residue levels in the edible pods.     

Distribution and phenotypic characteristics of common bean (Phaseolus vulgaris L.) nodulating bacteria in diverse soils

ABSTRACT

Bacteria were isolated from the root nodules using common bean as a trap host. Growth and morphological characteristics of the bacterial isolates were described on yeast extract mannitol mineral salts agar and broth media. The results showed that over 67% of the isolates produced extracellular polysaccharide with an entire margin and convex elevation. The others differentiated into cream yellow, cream white and milky white colouration with colony area ranging from 0.8 to 26?mm². The population levels of bacteria nodulating common bean varied in soils and were not affected by the cropping system. However, selected soil parameters greatly influenced the occurrence and distribution of these bacteria. The isolation of indigenous bacteria in all the soils with different cropping systems is an indication that the soils are favourable for nitrogen fixation. Based on the differences in cultural characteristics of the isolates, our data demonstrate the presence of high diversity of bacteria associated with bean nodules.     

Population structure and genetic differentiation among the USDA common bean (Phaseolus vulgaris L.) core collection

Genetic diversity data were collected from a large population of common bean (Phaseolus vulgaris L.) landraces representing the United States Department of Agriculture core collection. The data were based on microsatellite data from all linkage groups. A procedure was developed to determine if we collected sufficient marker data to adequately estimated pairwise diversity. The diversity data were used to define populations using distance and model-based approaches. Genetic differentiation and genetic isolation by distance data were collected. Diversity was also compared for markers linked and unlinked to domestication loci. Using a model-based approach, the landraces were divided into the traditional Middle American and Andean gene pools. Diversity was greater for the Middle American gene pool. Six Middle American and three Andean subpopulations were defined, and the Middle American subpopulations exhibited strong geographic identity. Unlike other studies, seed size varied considerably with subpopulations, and a number of the subpopulations contained landraces from multiple common bean races. All of the subpopulations were highly differentiated, with the Middle American subpopulations showing the greatest differentiation. Genetic isolation by distance was observed among the Middle American and Andean subpopulations but not among subpopulations within a gene pool. Within each gene pool, diversity was lower for markers linked to domestication loci.