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ARS Home » Southeast Area » Charleston, South Carolina » Vegetable Research » Research » Publications at this Location » Publication #339204

Research Project: Sustainable Approaches for Pest Management in Vegetable Crops

Location: Vegetable Research

Title: Genetic diversity and population structure of the endangered whorled sunflower, Helianthus verticillatus, at two sites in Georgia

item EDWARDS, TYLER - University Of Tennessee
item TRIGIANO, ROBERT - University Of Tennessee
item OWNLEY, BONNIE - University Of Tennessee
item WINDHAM, ALAN - University Of Tennessee
item Wadl, Phillip
item HODGES, MALCOLM - Nature Conservancy
item HADZIABDIC, DENITA - University Of Tennessee

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: N/A

Technical Abstract: Helianthus verticillatus, the whorled sunflower, is an endangered species endemic to only a few locations in Tennessee, Alabama, and Georgia. This sunflower is an aggressive grower and attractive to both plant enthusiasts and pollinators with its multiple, small yellow flowers in late fall. There is no conservation plan for this species because of large gaps in knowledge in the plant’s basic biology, and fine-scale population structure, as well as little census data is available. The objectives of this study were to better understand the fine-scale genetic diversity and the spatial population structure of H. verticillatus. Two small sites in Georgia separated by less than a kilometer of densely forested land were sampled. Fourteen published microsatellite loci from H. verticillatus were used to assess genetic diversity and population structure of the plants in the sampling areas. Our results indicated moderate genetic diversity, limited gene flow and high genetic differentiation among H. verticillatus subpopulations. Two distinct genetic clusters, one located on either side of the forested barrier, were detected, and furthermore, little gene flow was evident between the two groups. We found significant heterozygosity excess, indicating presence of population bottleneck due to recent reduction of population size. The standardized index of association (¯rd), a measure of linkage disequilibrium, was significantly different from zero, supporting the hypothesis of extensive and significant clonal reproduction among H. verticillatus subpopulations. Overall, these results have major implications for the population fitness, and survival of this species, and points to the immediate need to develop and implement a recovery plan for H. verticillatus.