Genetic diversity of Pometia tomentosa,a major constructive species of valley rainforest in Yunnan

【Objective】Pometia tomentosa is a rare and precious local tree species in Yunnan Province of China and it is also one of the major constructive species for valley rainforests. Understanding the genetic diversity and genetic structure of Pometia tomentosa could provide a guide for a seed collecting strategy to effect vegetation restoration in valley rainforests.【Method】Four populations with a total of 82 samples of Pometia tomentosa from the Xishuangbanna prefecture were studied. Simple sequence repeat(SSR)molecular technique was used to detect polymorphism of allelic fragments. POPGENE,version,1.32 GenAIEx 6.501 and STRUCTURE 2.3.3 were used to analyze the genetic diversity and genetic structure of populations.【Result】Eighty-eight alleles were detected by 19 pairs of SSR primers with an average of 4.632 per pair. The range of Shannon's information index(I)was 0.264-1.687 with a mean of 0.879. Polymorphism information content(PIC)varied from 0.128 to 0.729 with a mean of 0.422,while expected heterozygosity(He)varied from 0.138 to 0.765 with a mean of 0.473. The average values of I and He for the 4 populations were 0.785 and 0.437 respectively. The average of genetic differentiation(F_ST)was 0.069 and gene flow(Nm)was 3.363,which means a relatively low genetic differentiation among the populations. The 4 populations were divided into 4 groups based on STRUCTURE analysis. UPGMA clustering indicated that the 4 populations were clustered into 2 branches,one of which consisted of a natural population in Caiyanghe,an artificial population in Puwen and a natural population in Puwen. The other branch contained only a natural population in Mengyang.【Conclusion】The genetic diversity of Pometia tomentosa is only medium at both the species and the population levels. Genetic variation comes mainly from within populations,so individuals within populations should be targeted for selection and conservation. In the recovery of valley rainforests,the genetic diversity of natural populations could be set as a target,which can be achieved by scientific planning of the seed collection