Association Mapping of Morphological Traits in Gossypium arboreum Accessions.

Advances in the use of diploid Asiatic species in cotton breeding require an understanding of the relatedness and ancestry of diploid cotton accessions, and identification of SSR markers associated with agronomically important phenotypic traits. Seventy-nine Gossypium arboreum germplasm accessions from eleven geographic regions of Africa, Asia and Europe were evaluated for 11 phenotypic traits (leaf shape, leaf color, petal color, petal spot presence, pollen color, foliar nectary, floral nectary, fuzz, lint color and lint percentage), and genotyped with 96 genome-wide polymorphic SSR markers. Population structure analysis identified seven main clusters for the accessions which corresponded to the major geographic areas, indicating agreement between genetic and predefined populations. The general linear model method was used to disclose marker-trait associations. Marker-trait associations were investigated by fitting single marker regression models for phenotypic traits with correction for population structure. This work illustrates the potential of association mapping in diploid cotton, because existing phenotypic data, a modest number of SSR markers, and a pioneering statistical analysis, identified interesting associations.