Genetic diversity among "Qamgur" varieties in China revealed by SSR markers

"Qamgur", a type of turnip (Brassica rapa ssp. rapa), is a special food of the Uyghur people living in Xinjiang, the northwest of China. In the present study, SSR markers developed for various Brassica rapa subspecies were tested for their transferability to turnip and used to analyze genetic diversity in "Qamgur" and other Chinese turnip varieties. A total of 18 "Qamgur" and 12 other varieties were genotyped with 170 SSR markers developed for Brassica rapa ssp. 80% markers could amplify products, out of which 52 produced scorable bands. The 52 markers generated 153 alleles and 39 detected polymorphisms in 30 varieties. The average Nei's genetic distance ranged from 0.156 to 0.349 in the whole collection, but the genetic variation was narrower in "Qamgur" varieties than in other varieties. Phylogenetic analysis showed that the 18 "Qamgur" varieties were always clustered together and distinct from the other varieties, which was supported by the data of principle component and population structure analyses. These results suggest that the SSR markers developed from other Brassica rapa subspecies could be used in genetic study in turnip and "Qamgur" will be valuable resources for developing new cultivars.