Study On Genetic Diversity Of Rheum Tanguticum In Qinghai Province Based On MatK+rbcL Barcoding And RAPD Markers

Rheum tanguticum,belongs to the Rheum genus in the Polygonaceae family.the wild resources are mainly distributed in the area with the average altitude from 3000 m to 4000 m.The wild resources of R.tanguticum have been vulnerable.In this study,the characteristics of genetic diversity and genetic structure were detected by matK+rbcL barcoding and RAPD molecular markers,the main results were as follows:1.The complete chloroplast genome of the R.tanguticum has been reconstructed with High-throughput sequencing technologies.The genome was 161 054 bp in length,exhibiting a typical quadripartite structure of the large single-copy regions(LSC,86 441 bp),small single-copy regions(SSC,12 745 bp)and a pair of inverted repeats(IRs,30 934 bp each).The chloroplast genome contains 164 genes,including 111protein-coding genes,45 transfer RNA genes and 8 ribosomal RNA genes.2.180 individuals from 36 populations of R.tanguticum were analyzed based on matK+rbcL barcoding of chloroplast DNA.1634-bp fragment and 10 haplotypes were obtained.The haplotype diversity of MH XM3 population was the highest,and the rest of 25 populations had the lowest haplotype diversity,such as DT HLZ and HZ WF population.AMOVA analysis indicated that the genetic differentiation mainly occured among populations of R.tanguticum,which of 61.77% occured among populations and 38.23% occured between individuals of population.Haplotypes network analysis and phylogenetic tree analysis showed that genetic differentiation was existed within the R.tanguticum.The mismatch distribution results suggested that R.tanguticum was relatively stable in the process of evolution,and without any experience of population expansion.3.135 individuals from 27 populations of R.tanguticum were analyzed based on RAPD method with 7 primers,79.32% polymorphism bands were obtained,the observed number of alleles(Na),the effective number of alleles(Ne),expected heterozygosity(He)and the Shinnon information index(I)were all highest in the GD QZS population,while MH XM4 population had the lowest value of genetic diversityparameters.The total genetic diversity(Ht)and intraspecific genetic diversity(Hs)of R.tanguticum were 0.1837 and 0.0144,AMOVA analysis indicated that the genetic differentiation mainly occured among populations of R.tanguticum,which of 81.30%occured among populations and 18.70% occured between individuals of population,which showed that the total genetic variation mainly existed between populations,and the genetic differences between MH XM3 and HZ TZX was the greatest,while the MQ WDR1 and DR CMBE population has the smallest genetic differences.