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Abstract
Scientific information on the A genome species of Gossypium is limited due to their decline as crop species and low levels of marker polymorphism. As the A subgenome of the allotetraploid species of Gossypium is contributed by A genome progenitors, studies on the A genome will help us understand the evolution of polyploids. We compared DNA marker order along the chromosomes of A, D and At genomes of Gossypium by constructing a comprehensive A genome RFLP linkage map from an interspecific F2 population of G. arboreum x G. herbaceum. Chromosomal structural rearrangements are more pronounced among A and At than A and D genomes, perhaps owing to the higher level of repetitive DNA in A and At genomes. We also compared QTL governing the floral morphological variation among diploid and tetraploid interspecific F2 populations. Our study indicated possible silencing and subfuntionalization of homeologous QTL in the tetraploid genome. Index words: Comparative mapping, comparative QTL mapping, genome evolution, Gossypium, homeologs, inversions, intergenomic interactions, orthologs, petal spot, polyploidy, RFLP, subfunctionalization, translocations, tetraploid subgenomes. COMPARISON OF DNA MARKER ORDER AND FLORAL TRAIT EVOLUTION AMONG DIPLOID AND TETRAPLOID GENOMES OF GOSSYPIUM by APARNA DESAI B.Sc. Agriculture, Acharya N. G. Ranga Agricultural University, A.P., India, 1996 A Thesis Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE ATHENS, GEORGIA 2005