Abstract:

Sequence Related Amplified Polymorphism (SRAP) analysis was applied to study the genetic diversity of Paeonia ludlowii, a species only distributed in Tibet of China. Sixteen pairs of SRAP primers were used to evaluate the genetic diversity of 79 samples from five natural populations. A total of 396 valid loci were obtained, of which 357 were exhibited polymorphism. The percentage of polymorphic loci (P_pl) and the mean diversity estimated with Shannon's index of phenotypic diversity(Η_sp) at species level were 90.15% and 0.252 1, respectively.At population level, P_pl was 31.82% and Shannon's index (H_o) ranged from 0.069 4 to 0.342 8, with an average value(Η_pop) of 0.130 7. Among the five populations, population C was especially more diverse(P_pl=82.32%,H_o=0.342 8). Those results indicated that there was a relatively high level of intraspecific genetic diversity. Analysis of molecular variance(AMOVA) demonstrated that a high degree of genetic differentiation occurred among the populations (Φ_{ST =0.415 8,P<0.001). The proportion of genetic variation among populations was 41.58%, while the proportion within population was 58.42%. A similar analysis result was exhibited by the genetic differential index(GST) of 0.430 9 and the proportion of diversity among populations with Shannon's index of 0.481 6. Mantel test showed that there was no significant correlation between geographical distance and genetic distance (r=0.597 5,P=0.905 5) among populations. A dendrogram conducted by UPGMA method using NTSYSPC(2.1) demonstrated that the range of genetic similarity coefficient was 0.47-0.99. The most of the individuals came from the same population had close genetic relationship, such as population of B, D, E,but individuals from population C could not be clustered together completely. A strategy for the conservation and utilization of P. ludlowii based on genetic diversity was proposed.}

Key words: Paeonia ludlowii, SRAP, population, genetic diversity, genetic differentiation