ALLELIC DIVERSITY OF HIGH-MOLECULAR-WEIGHT GLUTENIN PROTEIN SUBUNITS IN NATURAL-POPULATIONS OF DASYPYRUM-VILLOSUM (L) CANDARGY

Dasypyrum villosum (L.) Candargy (2n = 14, V genome) is a wild, alloga mous, diploid grass species that is a potential genetic resource for w heat improvement. The diversity of high-molecular-weight (HMW) gluteni n subunits of the seed storage proteins of this species was examined i n populations sampled in their natural habitats in Italy and Yugoslavi a where the species is widely distributed. The results of selfed proge ny tests confirmed that the allelic variation of HMW-glutenin subunits in D. villosum is controlled by a single locus (Glu-V1). Fourteen all eles at Glu-V1 were found among 982 individuals representing 12 popula tions from Italy and two from Yugoslavia, with a mean of seven alleles per population. Among the 14 Glu-V1 alleles, one produced no HMW-glut enin subunits, ten coded for a single subunit, and three for two subun its. The mobilities of all the subunits in SDS-PAGE gels were greater than that of reference subunit 7 of Triticum aestivum cv Chinese Sprin g. Eight of the alleles were relatively abundant (mean frequency over all populations ranged from 0.08 to 0.17) and distributed widely among the 14 populations (8 to 14); five of the alleles were rare (0.003 to 0.02 1) and found in only 1 to 5 populations. The frequencies of two alleles could not be individually estimated because of the similar ele ctrophoretic mobility of their subunits. The multiple-allelic diversit y at Glu-V1 was high (H(e) ranged from 0.700 to 0.857) but similar fro m population to population. Overall, about 7% of the total allelic var iation was distributed among populations (G(st) = 0.072), and more tha n 90% within populations. Whether the allelic variation at Glu-V1 is s ubject to natural selection is unknown, but the discovery of the homoz ygous null Glu-V1 alleles in the present study may be useful in pursui ng this question. The multiple-allelic diversity in Glu-V1 presents th e plant breeder with an opportunity to evaluate and select the most us eful alleles for transfer to wheat. The importance of an evaluation ge netic diversity in a wild species before interspecific gene transfers are attempted is well illustrated in this study.