Submitted to: International Cotton Genome Initiative Workshop
Publication Type: Proceedings
Publication Acceptance Date: September 18, 2006
Publication Date: September 18, 2006
Citation: Ulloa, M., Frelichowski, J.E., Stewart, J.M. 2006. Diversity among Landraces of Gossypium hirsutum and D-genome Species Determined by SSR Markers. International Cotton Genome Initiative Workshop. Brasilia DF, Brazil. p. 13-14.
New genetic research tools, such as molecular markers, enable us to better understand the genetic parameters associated with diversity and their relationships with desirable production and quality traits in cotton. Morphological traits and microsatellite (SSR) marker data were collected from a field planting of over 450 landrace accessions of Gossypium hirsutum and all known D-genome diploid species collected during recent exploration trips. Thirty morphological traits and 125 selected SSR markers for which chromosomal locations were known were evaluated and assessed on these accessions in Shafter, CA USA and Tecoman, Colima Mex. Origins of allelic diversity and genic regions revealed by microsatellites derived from EST and genomic DNA sequences of polymorphic amplicons suggested four scenarios of transferability and rearrangement of amplicons in the allotetraploid AD cottons (G. hirsutum and G. barbadense) compared to the progenitor A and D diploid genomes. The variations in the morphological and in the SSR data were used separately to cluster the accessions by relatedness. SSR marker data was more helpful than morphological data in characterizing the diversity among the D species according to their origin of collection. Estimates of genetic similarities among all taxa showed extensive allelic diversity for these genomes. Partial results indicated that tetraploid cottons underwent a higher rate of DNA rearrangement than expected at the gene level following allopolyploidization. This research will be helpful in updating the morphological characterization of the collection, in integrating portable mapped SSRs to understand the genomic basis of genetic diversity of G. hirsutum, and in revealing unique sources of genetic variation in the collection.