Plant & Animal Genome IX Conference

Workshop: Cotton
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COMPARATIVE PHYSICAL MAPPING IN COTTON (GOSSYPIUM)

University of Georgia, Department of Crop and Soil Science, Athens, GA 30602

Physical mapping of diploid and tetraploid cotton species in our lab facilitates ongoing research into genome evolutionary processes that occur subsequent to polyploidization. Our goal is to construct physical genetic maps for cultivated tetraploid species G. barbadense and G. hirsutum (each with genome constitution AD) and the wild diploid species G. raimondii (D genome). As an example, here we focus on two pairs of homoeologous chromosomes (6,25 and 9,23) from G. barbadense (cv. Pima) and corresponding homologues 10 and 6 from G. raimondii. BAC libraries for the two species provide 5X and 9X genome coverage respectively. Probes for library hybridizations include several classes of genomic and cDNA clones of known relationship on genetic maps constructed for the two species in our lab. Library screenings reveal approximately expected clones/probe based on coverage, although variance among clones is high. Contigs for the two species are assembled from HindIII restriction digest fingerprints of BACs. For the polyploid taxon, we explore various methods, including BAC-RF, for assigning assembled contigs to subgenome.