Analysis Of Genetic Diversity Based On SSR Markers And ITS And CpDNA Sequences Of Rosa Roxburghii Tratt

Rosa roxburghii Tratt.(Rosaceae,2n=2x=14)mainly distributed in China,the Guizhou Province is particularly rich in germplasm resources.In the past,genomic information was lacking due to little knowledge of the genetic background of R.roxburghii,resulting in extremely limited genetic markers available.In this study,the SSR markers which based on transcriptome and genome research was used,and combined with ITS and cpDNA sequences.29 wild R.roxburghii populations,including Guizhou Province,Yunnan Province,Sichuan Province,Chongqing City,Hunan Province,Hubei Province and Shanxi Province provinces,genetic diversity,genetic structure and phylogeography of information are analyzed.The main findings are as follows:1.Combined with EST-SSR and nSSR primers of 29 wild R.roxburghii populations genetic diversity analysis,the results showed that compared with other Rosaceae plants,wild R.roxburghii genetic diversity of populations in moderate to high level(Na=4.00,Ne=3.11,I=1.14,Ho=0.84,He=0.67,Nei's=0.62),with what ZJ population contained the highest level of genetic diversity;the results appear nine nucleotide variation based on ITS sequence variation analysis,and accroding to the define 10 haplotypes showed moderate genetic diversity levels(Hd=0.247,?=0.00040),with SC population genetic diversity had the highest level;using the cpDNA haplotype of 29 populations analysis revealed the higher genetic diversity of R.roxburghii in chloroplast level(Hd=0.829,?=0.00131),and the genetic diversity of FQ and MX populations was the highest at the chloroplast level.2.The STRUCTURE analysis based on SSR markers showed that,29 R.roxburghii populations derived from 2 homologous gene library,can be divided into 3 groups: group of in Guizhou Province,group of out of Guizhou province(including Guizhou province BJ and DF populations),middle group(HY,QX,SC,ZJ);further Mantel detection showed that there was a significant positive correlation between genetic distance and geographic distance among the 14 populations in Guizhou(r=0.274,p=0.01).The results of the clustering of cpDNA sequences can be divided into three groups in all populations,Guizhou province BJ and DF populations exhibit farther genetic distance in the first group,while the HY and SC populations clustered into third group and consistent with SSR results.The results of cluster analysis based on the ITS sequence showed that the populations with only the ancestral haplotype(H-8)were clustered together,and the populations contain specific haplotypes showed a far genetic distance,and even clustered a single clade.Analysed of the above 3 kinds of markers.The results showed that the gene exchange frequent(Nem= 3.373,3.176 and 2.994)inhibited the genetic differentiation caused by genetic drift,it was the main reason of the result of R.roxburghii remained relatively low levels of genetic differentiation between groups(Fst= 0.069,0.136 and 0.143).3.Neutral tests based on ITS and cpDNA sequences showed that R.roxburghii populations with neutral evolution characteristics,and mismatch distribution analysis showed a single peak curve.The above description of R.roxburghii Germplasm in the evolutionary process experienced significant population expansion dynamic events.The phylogeography analysis based on the cpDNA sequence showed that the population expansion of R.roxburghii was estimated to occur between 647 073 and 217 848 years ago.Contiguous range expansion,past fragmentation and/or long distance colonization,restricted gene flow with isolation by distance were the important reasons for the formation of the current genetic diversity pattern.In addition,the pollen-seed mobility r was 0.1239,which was about 1: 8,which indicated that the gene exchange between populations mainly relied on seed propagation.This results in consistent with the fact that the R.roxburghii plant nanosoma led to pollen spread that relatively limited.4.Based on the above results,priority should be given to the implementation of local conservation strategies for populations with high genetic diversity ZJ,SC,FQ,MX and other populations.For some populations with specific haplotype such as ZT,XY,GZ and MN populations,can be protected in situ on the basis of the preservation of the seeds.