Submitted to: American Journal of Botany
Publication Type: Abstract Only
Publication Acceptance Date: 4/8/1997
Publication Date: N/A
Technical Abstract: Helianthus annuus L., sunflower, is one of the few crops of worldwide importance that originated in the continental United States. Genetic variation at 20 isozyme loci was surveyed from 146 germplasm accessions of wild and domesticated sunflower and related species via newly optimized starch gel electrophoretic protocols, yielding one of the more extensive data sets of allelic frequencies available for sunflowers. Standard measures of genetic polymorphism were calculated and inter-accession distance matrices were analyzed to assess systematic relationships among domesticated and wild sunflower accessions and related wild species. Wild sunflower populations exhibit geographically-structured variation. Accessions from the Great Plains included greater allelic diversity than did wild sunflowers for the western U. S., and are genetically somewhat divergent from wild accessions collected in California and the Southwest. Wild and domesticated sunflowers are genetically divergent, primarily because of differences in the frequencies of common alleles. Oilseed and confectionery sunflowers apparently comprise a distinct lineage, but ornamental domesticates are relatively divergent from other domesticated types.