ISOZYME VARIATION IN CULTIVATED OAT AND ITS PROGENITOR SPECIES, AVENA-STERILIS L

Effective identification of wild accessions with potential to enhance variation for complex, low heritability traits is a prerequisite to broader utilization of conserved genetic resources. In two previous studies, 23 enzyme systems were assayed in 405 oat cultivars (Avena sativa L. and A. byzantina C. Koch) and in 1005 accessions of the progenitor species. A. sterilis L. The objectives of the present report were to (i) compare isozymic variation in cultivated oat with a broad geographical sample of accessions of the progenitor species and (ii) propose a strategy to assist in the efficient sampling of progenitor germplasm by North American oat breeders. Avena sterilis displayed a greater level of isozymic diversity compared to cultivated germplasm based upon number and frequencies of variants. Three sampling strategies are discussed whereby a representative core of A. sterilis accessions could be selected from the progenitor germplasm pool. A combined strategy is outlined that incorporates elements of all three, with selection of accessions from (i) the center of isozymic diversity (Turkey), (ii) six clusters of A. sterilis accessions identified by multivariate analysis of genetic distances between accessions without regard to provenance data, and (iii) those accessions with variants present at intermediate to high frequencies in A. sterilis from individual countries or clusters yet absent in cultivated germplasm. Selected A. sterilis accessions could be used in combining ability analyses with cultivated germplasm. Subsequent, more extensive, exploitation of the germplasm collection might be based on results from these exploratory evaluations of breeding potential.