The endangered plant Tetracentron sinense Oliv. (Tetracentraceae) populations: genetic diversity, structure and dynamic history based on SSR markers for its conservation

Abstract

Tetracentron sinense Oliver, as a tertiary living fossil, a dramatic decline in T. sinense population amounts, genetic resources depletion and recent human activities have shaped habitat fragmentation of relict and endangered plants, although there is ample evidence of its great medicinal, economic and ecological value. However, little is known about the genetic evolution of T. sinense. With this work, 193 individuals from 22 natural T. sinense populations regarding its genetic diversity, genetic differentiation, and demographic history using simple sequence repeat (SSR) markers to clarify its evolution models and develop scientific conservation strategies. We evaluated the genetic diversity, population structure and demographic history of 193 T. sinense individuals based on 14 SSR markers. At the species level, PPL, I and He were 100%, 1.631 and 0.559, respectively. At the population level, Na, Ne, I, Ho and He were 3.221, 2.505, 0.937, 0.434 and 0.566, respectively. The results revealed high genetic diversity at the species level and within populations. Individuals were structured into three main clusters (K = 3) with significant genetic differentiation (Fst = 0.31). Demographic history analysis showed that T. sinense differentiated according to the radial differentiation model. The differentiation occurred 1.115×104 to 2.23×104 years ago during Last Glacial Maximum. The twenty–two T. sinense populations revealed moderate genetic diversity and seemed to be structured into three clusters with high differentiation suggesting its preserved the evolutionary potential and the Hengduan Mountains and Qinling Mountains act as the two major glacial refuges. High differentiation caused by long–term geographic isolation may lead to the population extinction. The radial differentiation model suggested that T. sinense originated from common ancestor.