PROGRESS REPORT FOR THE EVALUATION OF COTTON LANDRACES FROM THE USDA-ARS COTTON GERMPLASM COLLECTION

摘要

A set of 434 G. hirsutum landrace accessions were selected from the U.S. Cotton Germplasm Collection, USDA-ARS and planted in several years and environments which include Shafter, CA and Tecoman, Colima, Mexico. The objectives are the characterizationof the accessions for over 30 morphological traits and 100 microsatellite (SSR) markers, including recently developed and genetically mapped SSRs. Morphological traits may have potential for cultivar improvement and are important for conservation. SSR data will be useful to compare genetic diversity of the landraces throughout the cotton genome and enable advanced analyses. Five morphological traits and 24 SSR markers were used to compute Jaccard’s coefficient and construct different dendrograms of 204 select accessions, which were chosen to represent their natural origin across 18 states of Mexico. The accessions did not cluster clearly by origin in the dendrograms suggesting gene flow and introgression of traits/alleles throughout different regionsof the natural habitat of the landraces. The SSR marker data did group many more accessions by their origin than the trait data. A small comparison of 7 specific markers specific to homoeologous chromosomes showed a difference in the genetic diversity revealed. This research will continue to compile more trait and chromosome specific SSR markers to describe genetic variation in the landrace collection, and to use this information to improve the maintenance and utility of the germplasm collection.