Genetic Relationship And Species Identification of Dioscorea Polystachya Turcz. In Yams Determined By ISSR, ISAP, SRAP And SCAR Markers

Abstract Dioscorea polystachya Turcz. is the authentic herb Yam in Chinese traditional medicine. In the medicine market, some relative species are misused as “Yams”, such as D. alata L., D. exalata C.T. Ting & M.C. Chang, D. persimili Prain et Burkill, D. fordii Prain et Burkill and D. japonica Thunb. In order to estimate the genetic relationships among those species and develop a rapid and accurate method for D. polystachya identification, Inter Simple Sequence Repeat (ISSR), Intron Sequence Amplified Polymorphism (ISAP), Sequence-Related Amplified Polymorphism (SRAP) and Sequence Characterized Amplified Region (SCAR) were conducted in this study. Combining ISSR, ISAP and SRAP markers, a high degree of variation among the Dioscorea species was detected. Moreover, a relatively high gene flow (Nm = 0.3293) in those species was observed. The main reason for this phenomenon might be there were genepools exchanging in the wild materials. The phylogenetic tree and genetic similarity results showed D. japonica had the closest genetic relationship with D. polystachya. Considering the lowest inter-species variation observed in D. polystachya and the highest genetic divergence within D. japonica, we suggested the taxonomy of one species complex D. polystachya-D. japonica for breeding and conservation purpose. The phylogeny data in this study indicated D. alata and D. persimilis should be independent species respectively instead of cultigens. Furthermore, a SCAR marker was developed and could be used to discriminate the authentic herb D. polystachya from other confused Dioscorea species. Overall, the results are useful as guidelines for breeding programs and conservation actions.