[Genetic diversity of endangered plant Torreya jackii: a study with RAPD markers]

With random amplified polymorphic DNA (RAPD) techniques, this paper studied the genetic diversity and genetic differentiation of Torreya jackii, an endangered plant endemic to China. In the 180 individuals of 9 T. jackii natural populations, 180 repetitive loci were detected by using 12 random primers, among which, 119 were polymorphic. At species level, the percentage of polymorphic loci (P) was 66.11%, and the genetic diversity estimated by Shannon information index (I) and Nei's index (h) was 0.3087 and 0.2015, respectively, suggesting that the genetic diversity at species level was relatively high. However, at population level, the genetic diversity was relatively low (P = 23.76% , I = 0.1221, and h = 0.0813). The analysis of molecular variance (AMOVA) showed that 42.57% of genetic variance was found within populations, and 57.43% of it was resided among populations. The coefficient of gene differentiation (G(st)) was 0.5965, indicating the high genetic differentiation among the populations of T. jackii, and the gene flow among the populations was quite low, being 0.3382. The bottleneck effect, population isolation, and low gene flow among populations would have contributed to such a population genetic structure in T. jackii. The averaged genetic distance among 9 T. jackii populations was 0.1630. By using the unweighted pair group method with arithmetic mean (UPGMA), the 9 populations could be divided into two groups, i. e., Zhejiang group and Fujian group. It was proposed that in the ex situ conservation of T. jackii, the gcrmplasm transferring among populations should be avoided.