Genetic Diversity Among Chinese Pea (Pisum sativum L.) Landraces as Revealed by SSR Markers

To reveal the genetic diversity of China cultivated pea (Pisum sativum L.) and the genetic relationships among germplasm from different sowing area and provinces, a total of 1,221 landraces were sampled from 19 provinces in China consisting of 784 spring-sowing and 437 winter-sowing landrace. Using 21 sequence tagged microsatellites (STMS) markers, 104 polymorphic bands were detected with an average of total 4.95 alleles per locus and 3.10 (62.52%) effective alleles per locus for diversity analysis. Among the different provinces, the alleles of landrace group distributed evenly, whereas the number of effective alleles and the Shannon's information index (I) varied markedly. The largest genetic diversity appeared in landraces from Inner Mongolia, followed by Gansu, Sichuan, Yunnan, and Tibet, and Liaoning had the lowest genetic diversity. According to 3-dimension principal component analysis (PCA), 3 gene pools were detected in Chinese pea landraces, which were typically represented by the landraces from Inner Mongolia and Shaanxi (Gene Pool I), Henan (Gene Pool II), and other provinces (Gene Pool III). The pairwise Nei's (1978) genetic distance ranged from 5.159 to 27.586 in provinces. The provincial accessions were clustered into 2 groups and 8 subgroups with interactions to the gene pools. The cluster result suggested that the genetic diversity of Chinese pea landraces was associated with their ecological and geographical distribution.