ALLOZYME VARIATION IN DOMESTICATED ANNUAL SUNFLOWER AND ITS WILD RELATIVES

The annual sunflower (Helianthus annuus L.) is a morphologically and g enetically variable species composed of wild, weedy, and domesticated forms that are used for ornament, oilseed, and edible seeds. In this s tudy, we evaluated genetic variation in 146 germplasm accessions of wi ld and domesticated sunflowers using allozyme analysis. Results from t his survey showed that wild sunflower exhibits geographically structur ed genetic variation, as samples from the Great Plains region of the c entral United States were genetically divergent from accessions from C alifornia and the southwestern United States. Sunflower populations fr om the Great Plains harbored greater allelic diversity than did wild s unflower from the western United States. Comparison of genetic variabi lity in wild and domesticated sunflower by principal coordinate analys is showed these groups to be genetically divergent, in large part due to differences in the frequency of common alleles. Neighbor-Joining an alyses of domesticated H. annuus, wild H. annuus and two closely relat ed wild species (H. argophyllus T. & G. and H. petiolaris Nutt.) showe d that domesticated sunflowers form a genetically coherent group and t hat wild sunflowers from the Great Plains may include the most likely progenitor of domesticated sunflowers.