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 br oader utilization of conserved genetic resources. In two previous stud ies, 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 geograph ical 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 lev el of isozymic diversity compared to cultivated germplasm based upon n umber and frequencies of variants. Three sampling strategies are discu ssed whereby a representative core of A. sterilis accessions could be selected from the progenitor germplasm pool. A combined strategy is ou tlined that incorporates elements of all three, with selection of acce ssions from (i) the center of isozymic diversity (Turkey), (ii) six cl usters of A. sterilis accessions identified by multivariate analysis o f genetic distances between accessions without regard to provenance da ta, and (iii) those accessions with variants present at intermediate t o high frequencies in A. sterilis from individual countries or cluster s 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 breedi ng potential.