Genetic diversity of the two commercial tetraploid cotton species in the Gossypium Diversity Reference Set

A diversity reference set has been constructed for the Gossypium accessions in the U.S. National Cotton Germplasm Collection to facilitate more extensive evaluation and utilization of accessions held in the Collection. A set of 105 mapped simple sequence repeat markers were used to study the allelic diversity of 1,933 tetraploid Gossypium accessions representative of the range of diversity of the improved and wild accessions of G. hirsutum and G. barbadense. The reference set contained 410 G. barbadense accessions and 1,523 G. hirsutum accessions. Observed numbers of polymorphic and private bands indicated a greater diversity in G. hirsutum as compared to G. barbadense as well as in wild type accessions as compared to improved accessions in both species. The markers clearly differentiated the two species. Patterns of diversity within species were observed but not clearly delineated, with much overlap occurring between races and regions of origin for wild accessions and between historica...