Study On Molecular Phylogeography Of Paeonia Delavayi Based On Chloroplast DNA Non-coding Sequences

Paeonia delavayi belongs to Paeonia section Moutan DC.in the family Paeoniacene.It mainly distributs in Southwest China and is the most southerly of a peony distribution groups,so it has very important research value in the origin,evolution and geographical distribution of Peoria.P.delavayi is distributed in the various habitats,and there are rich morphological diversities and genetic diversities.Because of rich variations in flower color,especially yellow and purple which are rare in traditional peony cultivars,P.delavayi is an important source for breeding new varieties of ornamental peony.In this study,65 samples of the 21 natural P.delavayi populations which distributed in Yunnan and Sichuan provinces of China were used for molecular phylogeography research.We examined the chloroplast psbA-trnH sequence variation(non-coding spacer).By analyzing chloroplast DNA(cpDNA)sequence variation,haplotypes and calculated the genetic diversity indexes were obtained,including haplotype diversity,Hd,and nucleotide diversity,Pi.We built the N-J clustering figure by analysing the population structure of P.delavayi.And the M-L clustering figure was constructed using the sequences newly obained in this study and from GenBank.Haplotype network within the populations was constructed based on maximum parsimony standard while we conferred the phylogenetic relationship among haplotypes.The main results are as follows:(1)The sequences were aligned with 9 polymorphic sites and 7 cpDNA haplotypes were identified,which indicated that there is a high level of genetic variation across 21 populations of P.delavayi.(2)The variance among populations was much higher than that within populations,and the genetic differentiation among populations was very obvious.(3)The neighbor-joining tree showed that 7 cpDNA haplotypes were structured into two monophyletic groups.The M-L tree of 7 cpDNA haplotypes and other plants showed that it was reasonable to call the all populations as P.delavayi.(4)Haplotype network suggested that Deqin and ShangriLa is the distribution center of P.delavayi.It spread to around from Northwestern Yunnan,and spread southeast to central Yunnan plateau through Lijiang,Dali and the southwest of Sichuan.Molecular markers of cpDNA(non-coding spacer)sequencing reveal the genetic diversity and genetic structure of Paeonia delavayi in a certain extent,but the results could not reflect its rich phenotypic characteristics,which showed that the level ofgenetic variation of cpDNA(non-coding spacer)was lower than phenoty picvariation.In addition,the choice of the universal primer and sample size affected results of the study.