Genetic diversity and differentiation in Chimonanthus praecox and Ch. salicifolius (Calycanthaceae) as revealed by inter-simple sequence repeat (ISSR) markers

Chimonanthus praecox and Chimonanthus salicifolius are two native plants in China. In this study, the genetic diversity and differentiation within and among 17 natural populations of these two species were evaluated using inter-simple sequence repeat (ISSR) markers. Pronounced genetic differentiation occurred between these two species (Phi(ST) = 0.3364). For both species, the genetic diversity was low at the population level (Ch. praecox: PPL = 32.49%, h = 0.0968, I = 0.1488; Ch. salicifolius: PPL = 34.25%, h = 0.1192, I = 0.1777), but relatively higher at the species level (Ch. praecox: PPL = 86.03%, h = 0.1552, I = 0.2635; Ch. salicifolius: PPL = 81.25%, h = 0.2401, I = 03684). The hierarchical AMOVA revealed high levels of among-population genetic differentiation in both species, in-line with the gene differentiation coefficient and the limited among-population gene flow (Ch. praecox: Phi(ST) = 0.4650, G(ST) = 0.3784, N-m = 0.8213; Ch. salicifolius: Phi(ST) = 0.5912, G(ST) = 0.5036, N-m = 0.4929). A significant isolation-by-distance pattern was revealed in Ch. salicifolius (r = 0.703, P = 0.048), but not in Ch. praecox (r = 0.168. P = 0.185). Based on these data, effective conservation strategies were proposed for these two species. (c) 2012 Elsevier Ltd. All rights reserved.