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

item Hinze, Lori
item GAZAVE, ELODIE - Cornell University
item GORE, MICHAEL - Cornell University
item Fang, David
item Scheffler, Brian
item Yu, John
item JONES, DON - Cotton, Inc
item Frelichowski, James - Jim
item Percy, Richard

Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2016
Publication Date: 5/1/2016
Citation: Hinze, L.L., Gazave, E., Gore, M.A., Fang, D.D., Scheffler, B.E., Yu, J., Jones, D.C., Frelichowski, J.E., Percy, R.G. 2016. Genetic diversity of the two commercial tetraploid cotton species in the Gossypium Diversity Reference Set. Journal of Heredity. 107(3):274-286.

Interpretive Summary: Maintaining the genetic variation within the U.S. National Cotton Germplasm Collection is essential to assuring that the natural resources needed for future progress in crop health, yield, and fiber improvement are preserved. To effectively and efficiently preserve the genetic variation of the Collection, it is imperative that the extent and structure of this variation is understood. In an effort to analyze and characterize the genetic diversity available in the Collection, this research evaluated the molecular diversity in a subset of entries representing ~15% of the Collection and comprising entries from the two commercial tetraploid species as represented in the Collection. From this study we determined that it is possible to identify variation that differentiates lines within commercial species. We demonstrated that molecular markers could be used to identify introgression (or inter-crossing) among species. We also verified that introgression occurs at different rates and in different directions in the wild and improved plant types of each species. Characterization of the collection with molecular markers also allows breeders and geneticists to make more informed choices in their improvement efforts, resulting in superior cotton varieties and products for the consumer.

Technical Abstract: 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 historical and geographic breeding pools for cultivated accessions. Although the percentage of accessions showing introgression was higher among wild accessions than cultivars in both species, the average level of introgression within individual accessions, as indicated by species-specific bands, was much higher in wild accessions of G. hirsutum than in wild accessions of G. barbadense. The average level of introgression within individual accessions was higher in improved G. barbadense cultivars than in G. hirsutum cultivars. This molecular characterization reveals the levels and distributions of genetic diversity that will allow for better exploration and utilization of cotton genetic resources.