Variation in Physical and Chemical Characteristics of Common Bean (Phaseolus vulgaris L.) Grain along a Domestication Gradient
ABSTRACT The objective of this study was to compare six samples of Mexican wild common bean (Phaseolus vulgaris L.) against three landraces and three improved cultivars with respect to physical and chemical attributes, and the culinary quality potential of their grain. A completely randomized experimental design was used to characterize the twelve genotypes. Data were analyzed by analysis of variance and pair-wise comparison of the treatment means by the Tukey test. In addition, correlation and principal-component analysis (PCA) were carried out using twelve characteristics of raw and four of cooked wild and domesticated grains. The results show a larger variability of the physical and chemical characteristics in wild than in domesticated beans. The PCA confirmed that grain gigantism was the main physical characteristic resulting of domestication, whereas the protein and tryptophan contents tended to be higher in wild than domesticated genotypes. Some wild samples from Chihuahua and Durango, Mexico, showed to be a genetic resource to improve food quality, because of their richness in minerals, protein, lysine, tryptophan, and dietary fibers.
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ABSTRACT: Background Lipophilic antioxidants play dual key roles in edible seeds (i) as preservatives of cell integrity and seed viability by preventing the oxidation of fats, and (ii) as essential nutrients for human and animal life stock. It has been well documented that plant domestication and post-domestication evolution frequently resulted in increased seed size and palatability, and reduced seed dormancy. Nevertheless, and surprisingly, it is poorly understood how agricultural selection and cultivation affected the physiological fitness and the nutritional quality of seeds. Fabaceae have the greatest number of crop species of all plant families, and most of them are cultivated for their highly nutritious edible seeds. Here, we evaluate whether evolution of plants under cultivation has altered the integrated system formed by membranes (fatty acids) and lipophilic antioxidants (carotenoids and tocopherols), in the ten most economically important grain legumes and their closest wild relatives, i.e.: Arachis(peanut), Cicer(chickpea), Glycine(soybean), Lathyrus(vetch), Lens(lentil), Lupinus(lupin), Phaseolus(bean), Pisum(pea), Vicia(faba bean) and Vigna(cowpea).ResultsUnexpectedly, we found that following domestication, the contents of carotenoids, including lutein and zeaxanthin, decreased in all ten species (total carotenoid content decreased 48% in average). Furthermore, the composition of carotenoids changed, whereby some carotenoids were lost in most of the crops. An undirected change in the contents of tocopherols and fatty acids was found, with contents increasing in some species and decreasing in others, independently of the changes in carotenoids. In some species, polyunsaturated fatty acids (linolenic acid especially), ¿-tocopherol and ¿-tocopherol decreased following domestication.Conclusions The changes in carotenoids, tocopherols and fatty acids are likely side-effects of the selection for other desired traits such as the loss of seed dormancy and dispersal mechanisms, and selection for seed storability and taste. This work may serve as baseline to broaden our knowledge on the integrated changes on crop fitness and nutritional quality following domestication.BMC Plant Biology 12/2014; 14(1):385. DOI:10.1186/s12870-014-0385-1 · 3.94 Impact Factor