Characterization of the bean core collection : II. Phaseolin and total protein in cultivated Mesoamerican beans
1994
Vivas Arce, Alexandra | Munoz, C. | Lareo, Leonardo Rene | Beebe, Stephen | Ochoa, Ivan
Total protein (TP) content, phaseolin (Phs) content as percentage of total protein, and Phs type were evaluated on 530 accessions of Mesoamerican origin in the bean (Phaseolus vulgaris) core collection. TP content was measured by a Near Infrared Reflectance Spectroscope. Phs content was estimated by laser densitometry of 1D-SDS-PAGE gels. Typing was done by visual comparison of protein bands of unknowns and standards on gels designed specifically for Phs. TP content varied from 15.6-28.1 percent of flour (x= 21.3; sd=2.2). Phs constituted from 30-60 percent of total soluble protein (x=45 percent sd=6 percent), thus confirming that Phas is the major storage protein of beans. The most common Phs types were S, Sb and Sd, as reported previously respectively. Forty-six genotypes with Phs M were identified or 9.1 percent of the reported in very few genotypes, may be due to the manner in which the core collection was formed, which may have favored uncommon types. Additionally, types M1 and M15 were identified for the first time in landraces in 3 and 2 genotypes respectively. Types M, M1 and M15 are relatively common in wild beans in Mexico. Their appearance in cultivated types may be due to chance introgression from wilds although the appearance of M Phs in a sizable proportion of landraces merits suggests that yet another wild population may have undergone domestication. A few genotypes with Andean phs type T were also recognised, as was expected, since Andean types are grown in small proportion throughout the region.
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