The annual sunflower (Helianthus annuus L.) is a morphologically and genetically variable species composed of wild, weedy, and domesticated forms that are used for ornament, oilseed, and edible seeds. In this study, we evaluated genetic variation in 146 germplasm accessions of wild and domesticated sunflowers using allozyme analysis. Results from this survey showed that wild sunflower exhibits geographically structured genetic variation, as samples from the Great Plains region of the central United States were genetically divergent from accessions from California and the southwestern United States. Sunflower populations from the Great Plains harbored greater allelic diversity than did wild sunflower from the western United States. Comparison of genetic variability in wild and domesticated sunflower by principal coordinate analysis showed these groups to be genetically divergent, in large part due to differences in the frequency of common alleles. Neighbor-Joining analyses of domesticated H. annuus, wild H. annuus and two closely related wild species (H. argophyllus T. & G. and H. petiolaris Nutt.) showed that domesticated sunflowers form a genetically coherent group and that wild sunflowers from the Great Plains may include the most likely progenitor of domesticated sunflowers. Keywords Helianthus annuus, Allozymes, Crop evolution, Genetic diversity Disciplines Botany | Genetics | Plant Breeding and Genetics CommentsThis article is from Theoretical and Applied Genetics 95 (1997): 532, doi:10.1007/s001220050594. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.

Ideotype breeding in common bean (Phaseolus vulgaris L.) has emphasized the selection of modified morphological traits that include upright, Type II (indeterminate) growth habit. Progress in the medium‐seeded (⊄40 g/100 seed) pinto bean appeared to have been limited by negative linkages between small seed size (⊄20 g/100 seed) and desired architectural traits. The objectives of this study were to determine the inheritance of seed weight and plant architecture, evaluate the genetic relationships among both traits, and to define a pinto bean ideotype for the humid midwestern USA. The genetic associations among three specific architectural traits, seed weight, and upright plant architecture were investigated in F2 and F2:3 generations at E. Lansing, MI, in 1990 and 1991, respectively. Upright plant architecture was estimated to be moderately heritable with narrow‐sense estimates ranging from HNS = 0.42 to 0.62. F2 data from 1206 individuals indicated that plant architecture and seed weight are not linked (r = 0.05, P = 0.08). Directional selection for high (>30 g/100 seed) or low (<24 g/100 seed) seed weight resulted in significant differences in the average number of seeds per pod and the average number of seeds per plant. These directional selection results provide evidence that a pinto bean ideotype will differ from the small‐seeded navy bean ideotype by having fewer pods per plant and fewer seeds per pod. Selection for medium‐seeded, upright (Type II) genotypes in other commercial classes would be greatly facilitated through the use of the pinto bean ideotype as a genetic bridge.

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