Genetic Diversity of the USDA Cabbage Collection Germplasm Using SSR Markers
Cabbage (Brassica oleraceavar. capitata) is an economically important vegetable crop across the globe. For centuries, it has been used as a staple food; however the phytonutrient profile, comprised of glucosinolates, carotenoids, and flavonoids is associated with human health and disease prevention. This study was conducted to assess the genetic relationship among cabbage germplasm available in the U.S. Department of Horticulture, Geneva, NY. A total of 350 accessions representing over 25 countries were screened for SSR markers and phenotypic characteristics including leaf shape, color, vigor, head shape and compactness, and glucosinolate profile in 2011. Results indicated that significant genetic variation exists within the USDA germplasm collection. The neighbor-joining tree (un-rooted dendrogram) based on Dice distance of 22 SSR markers formed four major clusters each with a group of sub-clusters containing up to 15 accessions. Our results suggest that while geography plays an important role accessions from several of countries appeared closely related based on the SSR marker data. This indicates that exchange of common cabbage germplasm among different geographical locations has taken place through public and private breeder programs.