Characterizing diversity based on phenotypes and molecular marker analyses of purple yam ( Dioscorea alata L.) germplasm in southern China

Purple yam ( Dioscorea alata L.), which is widely distributed in southern China, is characterized by great purple to red flesh or skin, as well as nutritional and medical values. However, their intraspecific genetic diversity remains unknown, which inhibits the germplasm innovation and variety protection of purple yams. In this study, genetic diversity of 26 landraces from southern China were carried out by using 18 phenotypic traits and 9 simple sequence repeat (SSR) markers, respectively. The results showed that three phenotypic traits of the leaf shape, leaf vein color and tuber flesh color, displayed higher Shannon's diversity index ( I ) and variation coefficient, which could identify the purple yam resources effectively. In addition, all accessions were divided into four groups at the Euclidean distance of 1.43, and the taxa has a high correlation with regional distribution of yam accessions, the purple yam germplasm from Jiangxi and Fujian province were mainly clustered into Group IV and Group III respectively. Based on the SSR markers analysis, the Euclidean distance among all germplasms ranged from 0.17 to 0.79, and the 26 landraces were also clearly separated into four clusters at the Euclidean distance of 0.49. Clustering results based on SSR markers and phenotypic traits were consistent roughly. Furthermore, population structure revealed the existence of three sub-populations in all accessions. These results demonstrate the genetic diversity and distinctness among the purple yam from southern China and provide a theoretical basis for the identification and utilization of purple yams.