Genetic diversity and population structure of castor (Ricinus communis L.) germplasm within the U.S. collection assessed with EST-SSR markers

Authors: Wang, Ming; DZIEVIT, MATTHEW - Iowa State University; CHEN, ZHENBANG - University Of Georgia; Morris, John - Brad; NORRIS, JESSICA - Emory University; BARKLEY, NOELLE - International Potato Center; Tonnis, Brandon; Pederson, Gary; YU, JIANMING - Iowa State University

Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2016
Publication Date: 10/14/2016
Publication URL: http://handle.nal.usda.gov/10113/5636327
Citation: Wang, M.L., Dzievit, M., Chen, Z., Morris, J.B., Norris, J., Barkley, N.A., Tonnis, B.D., Pederson, G.A., Yu, J. 2016. Genetic diversity and population structure of castor (Ricinus communis L.) germplasm within the U.S. collection assessed with EST-SSR markers. Genome. 60:193-200. https://doi.org/10.1139/gen-2016-0116.
DOI: https://doi.org/10.1139/gen-2016-0116

Interpretive Summary: Castor is an important oilseed crop and although its oil is inedible, it has multiple industrial and pharmaceutical applications. The entire U.S. castor germplasm collection was previously screened for oil content and fatty acid composition, but its genetic diversity and population structure has not been determined. Based on the screening results of oil content, fatty acid composition, and country origins, 574 accessions were selected and genotyped with 22 polymorphic EST-SSR markers. The results from cluster analysis, population structure, and principal component analysis were consistent, and partitioned accessions into four subpopulations. Although there were certain levels of admixtures among groups, these clusters and subpopulations aligned with geographic origins. Both divergent and redundant accessions were identified in this study. The U.S. castor germplasm collection encompasses a moderately high level of genetic diversity (0.53). The results obtained here will be useful for choosing accessions as parents to make crosses in breeding programs and prioritizing accessions for regeneration to improve germplasm management. A subset of 230 accessions was selected and will be planted in the field for establishing a core collection of the U.S. castor germplasm. Further evaluation of the U.S. castor germplasm collection is also discussed.

Technical Abstract: Castor is an important oilseed crop and although its oil is inedible, it has multiple industrial and pharmaceutical applications. The entire U.S. castor germplasm collection was previously screened for oil content and fatty acid composition, but its genetic diversity and population structure has not been determined. Based on the screening results of oil content, fatty acid composition, and country origins, 574 accessions were selected and genotyped with 22 polymorphic EST-SSR markers. The results from cluster analysis, population structure, and principal component analysis were consistent, and partitioned accessions into four subpopulations. Although there were certain levels of admixtures among groups, these clusters and subpopulations aligned with geographic origins. Both divergent and redundant accessions were identified in this study. The U.S. castor germplasm collection encompasses a moderately high level of genetic diversity (0.53). The results obtained here will be useful for choosing accessions as parents to make crosses in breeding programs and prioritizing accessions for regeneration to improve germplasm management. A subset of 230 accessions was selected and will be planted in the field for establishing a core collection of the U.S. castor germplasm. Further evaluation of the U.S. castor germplasm collection is also discussed.