High genetic differentiation and variation as revealed by ISSR marker in Pseudotaxus chienii (Taxaceae), an old rare conifer endemic to China

Pseudotaxus chienii (Taxaceae) is an endangered conifer species endemic to China, with a historically disjunct distribution pattern. Eleven populations sampled throughout its range were examined using inter-simple sequence repeats (ISSR) markers. Twenty primers generated 242 bands, and each detected polymorphic loci, with 73.14% of polymorphic loci overall. The estimate for θB was 0.5306, whereas GST and ΦST values were 0.6146 and 0.6401, respectively. 50.62% of the total diversity based on Shannon's index of phenetic diversity was attributed to among populations, which was consistent with the θB estimation. Compared with other conifers, remarkable genetic differentiation occurred among P. chienii populations. A Mantel test indicated that pairwise values of θB were significantly related with geographical distances between populations (r = 0.676, P = 0.001). In terms of the above results, conservation strategies and maintenance plans of P. chienii were recommended.