Genetic diversity in natural populations of Chimonanthus praecox (L.) Link revealed by SRAP markers.

The genetic diversity and genetic structure of natural populations of Chimonanthus praecox(L.) Link,were analyzed using Sequence-related Amplified Polymorphism(SRAP)markers.One hundred and fifty accessions from 5 natural populations were used in this study.Seven SRAP primer combinations revealed 170 legible bands of which 41 were polymorphic markers.The average proportion of polymorphic loci PPL was 83.41%.Gene diversity(h)was from 0.21 to 0.25(average 0.22),Shannon's Information index(I)was 0.34,coefficient of genetic differentiation(Gst)was 0.17 and the mean of gene flow estimated(Nm) was 2.40.The results of AMOVA indicated that the variance components within populations and among populations contributing to total genetic variance were 79.89% and 20.11%,among regions was 32.39% and within regions were 67.61%.There was obvious genetic differentiation among populations and among regions.UPGMA cluster analysis based on Nei's genetic distance indicated that the genetic distances were closely related to corresponding geographic distances among populations,2-way Mantel test Matrix correlation r was 0.89.Conservation and utilization strategies for the species should be therefore emphasized on conserving as many as possible the existing populations,and selecting genetic diversity within populations considering the current conditions of severe population fragmentation and losses.