Molecular and Genetic Diversity of Cultivars in the U.S. Cotton Germplasm Collection

Although a large range of untapped genetic diversity exists within the U.S. Cotton Germplasm Collection, much of this diversity has not been characterized and its sources identified.  Our objective in this study was to characterize a subset of cultivated G. hirsutum germplasm within the collection using phenotypic and molecular tools, with the goals of determining the level of genetic variation present in the cultivar subset and identifying useful variation.  Sixty-two Gossypium hirsutum cultivars (12 each from northern Africa, southern Africa, China, U.S. obsolete, and U.S. recent, along with 2 genetic standards) were grown in two environments with four replications to evaluate agronomic and fiber properties.  All cultivars were also genotyped with SSR markers to measure molecular diversity.