Genetic Diversity and Population Structure of Rhododendron longipedicellatum, an Endangered Species

Rhododendron longipedicellatum is an endangered species endemic to southeastern Yunnan, China. Assessment of genetic variation is critical for protecting endangered species. Therefore, we used EST-SSR markers to analyze the genetic characteristics of R. longipedicellatum. The results revealed high genetic diversity at the species level (He = 0.559, N-A = 9.529) and within populations (He = 0.507, N-A = 5.910) and moderate genetic differentiation between populations (F-ST = 0.083). In addition, more genetic variation existed within populations (91.25%) compared with variation among populations (8.75%). The STRUCTURE analysis showed that 150 individuals from five existing populations could best be divided into two genetic groups. At the population level, the neighbor-joining (NJ) tree and principal coordinates analysis (PCoA) analyses also divided them into two groups. In addition, Bottleneck analyses using the Two-Phase Model (TPM) and Stepwise Mutation Model (SMM) as well as the Garza-Williamson Index revealed widespread signatures of bottleneck events. These results provide vital information for scientifically formulating conservation strategies for the endangered R. longipedicellatum.