Phylogeography Of Myrica Nana,Endemic Plant Species Distributed In Yunnan-Guizhou Plateau

Dwarf arbutus(Myrica nana Cheval.,Myricaceae)is a perennial evergreen shrub of the genus Myrica.It is endemic to China's Yunnan-Guizhou Plateau,and extends to northeast of Yunnan,southwestern part of Guizhou and the southern edge of Sichuan.Its fruit tastes sour and sweat.The root can be used as medicine.Has a function of stopping bleeding and collaterals and diarrhea.The root skin external use to treat sores,water or scald and traumatic bleeding.it has high medicinal and economic value.Our study aims to 174 individuals from 19 populations of psbA-trnH+trnD-psbM combination of two chloroplast intergenic regions and 163 individuals from 19 populations of ribosomal ITS genes were used to study Phytogeography of the endemic plant dwarf arbutus in Yunnan-Guizhou Plateau.The study,to detect the genetic diversity and genetic structure of Myrica nana Cheval,Therefore,the historical dynamics,geographical distribution pattern and genesis of Myrica nana Cheval and the distribution of Myrica nana Cheval glacial shelters were discussed.Finally,a reasonable scientific basis and protection strategy for the conservation of germplasm resources of Myrica nana Cheval were proposed.The main findings are as follows:(1)The total length of the two chloroplast gene spacers of Myrica nana Cheval was 1026 bp and detected 15 variable sites,a total of 10 haplotypes,the haplotype of chloroplast genes was geographically mapped to the haplotype network map.And established a NJ(Neighbor-joining)tree.The results showed that the haplotype was divided into two major genetic groups by Wumeng-Mountain.The genetic variation of Wumeng-Mountain was more stable than that of Wumeng-Mountain.The chloroplast haplotype diversity was 0.7954 and the nucleotide diversity was 0.00255.Myrica nana Cheval has a medium level of genetic diversity.The length of ITS of Myrica nana Cheval was 553 bp,and detected 23 variable sites,a total of 13 haplotypes.The haplotype network map of the nuclear gene haplotype was mapped and the NJ tree was established.Results showed that haplotype H2 was an ancestral haplotype,with the widest distribution in the east and south of Wumeng-mountain,and the central part of the west and the eastern part of the population.The mismatch analysis showed that the whole population did not expand in scope.The results showed that the overall distribution wasdivided into two major genetic groups based on Wumeng Mountain.The nuclear haplotype diversity was 0.6690 and the nucleotide diversity was 0.00477.(2)Analysis of molecular variance(AMOVA)of chloroplast gene psbA-trnH+trnD-psbM and ribosomal gene ITS of Myrica nana Cheval.Both results showed that the genetic structure of Myrica nana Cheval was mainly divided into two groups based on the Wumen-Mountains.The mismatch analysis showed that the Myrica nana Cheval group had not experienced expansion recently.Both supported haplotype and ribosome gene haplotype geographic distribution and network relationship.(3)The cpDNA genotype of Myrica nana Cheval was mainly divided into two sides by the H2 and H3 special genotypes,and the genotype H2 of nrDNA was ancestral haplotype,which was distributed on both sides of the Wumeng-Mountain Range.At the same time,based on cpDNA genotype and nrDNA gene haplotype network map,mismatch analysis and(AMOVA)analysis,it indicated that there were at least two glacial shelters in the fourth major climate and environmental changes,which are located in the Wumen-Mountains.The Guizhou Plateau and the Yunnan Plateau on the side.Supporting the predecessor's research,Wumen-Mountain divided the Yunnan Plateau and Guizhou Plateau as the dividing line of the Yunnan-Guizhou Plateau.(4)Myrica nana Cheval is a unique and important special plant resource of Yunnan-Guizhou Plateau.It is dioecious,with a small number of populations and individuals,and serious damage.Based on our research,the Yunnan-Guizhou Plateau is used as a dividing line to protect it separately,according to each region,it has its haplotype distribution pattern and genetic diversity,which is divided into 5 blocks.They are the Guizhou Plateau on the eastern side of Wumeng-Mountain,the south of Wumeng Mountain,the central part of Yunnan Plateau,the Panzhihua area in Sichuan and the Dali area.The focus is on protecting the A and R populations in the eastern part of Wumeng-Mountain,the G population in the south of Wumeng-Mountain,the M population in the central part of the Yunnan Plateau,the P population in Panzhihua,Sichuan,and the D group in Dali.