Genetic Diversity and Population Structure of the USDA Sweetpotato (Ipomoea batatas) Germplasm Collections Using GBSpoly
Wadl, P. A., B. A. Olukolu, S. E. Branham, R. L. Jarret, G. C. Yencho, and D. M. Jackson.  2019.  HortScience, 54(9):S410.

Sweetpotato, Ipomoea batatas, plays a critical role in food security and is the third most important root crop worldwide following potatoes and cassava. Sweetpotato is an important crop in the United States (U.S.) and is valued at over $700 million dollars annually. The U.S. sweetpotato germplasm collection is maintained by the USDA-ARS, Plant Genetic Resources Conservation Unit. There is currently a lack of knowledge of the genetic diversity within this collection that supports sweetpotato crop improvement. To date, no genome-wide assessment of genetic diversity of this collection has been reported. In our study, population structure and genetic diversity of 417 sweetpotato accessions originating from 8 broad geographical regions (Africa, Australia, Caribbean, Central America, Far East, North America, Pacific Islands, and South America) were genotyped with over 30,000 SNPs using a genotyping-by-sequencing (GBS) protocol optimized for sweetpotato. A neighbor joining cladogram and principal coordinates analysis based on the genetic relationships among the accessions indicated three major groups (North American, South American, and remaining regions). Pairwise FST values between broad geographical regions based on the origin of accessions ranged from 0.017 (Far East–Pacific Islands) to 0.110 (Australia–South America) and supported the clustering of accessions based on genetic distances. The markers developed for use with this collection of accessions provide an important genomic resource for the sweetpotato community, and contribute to our understanding of the genetic diversity present in the U.S. sweetpotato genebank.