Distribution of allozymic alleles and genetic diversity in the American Barley Core Collection

A survey of allozymic alleles and genetic diversity was made for 151 access ions of the American Barley Core Collection. A total of 25 alleles at ten l oci were observed. Two loci were monomorphic. The average diversity index f or individual loci ranged between 0.026 and 0.649. Most significant differe nces in allelic frequency and genetic diversity value were found between sp ring and winter barley. Spring barley showed a greatly higher average diver sity than winter barley (t = 2.124, P = 0.071). The smallest differences in allelic frequencies and diversity values were observed between the two geo graphical regions, North and South America. Rare alleles were detected only in a few accessions. Seven rare alleles were associated with spring barley . The genetic similarities among the 151 accessions ranged from 0.20 to 1.0 0, which showed that a high level of genetic variability exists in this set of core accessions. Cluster analysis and principal coordinate analysis did not give clear-cut separation of different types of barley, but most of th e winter barley accessions were closely associated.