Studies On Conservation Genetics Of Camellia Perpetua

Camellia perpetua S.Y.Liang et L.D.Huang belongs to the genus Camellia（Theaceae）.Is the southwest guangxi karst landform,limestone endemic species.Because the high ornamental value and the economic value,the discovery by the frenzied pilfering,its population and the individual number decreases sharply.In this study,a fragment of the small single Copy（SSC）region（5191bp）of chloroplast DNA（cpDNA）（ndhF,rpl32,trnl-uag and CCSA four genes and their spacers）,10 pairs of microsatellite primers were selected and combined with whole chloroplast genome sequencing.The genetic diversity,genetic differentiation and genetic structure of 351 individuals from 12 species of C.perpetua was analyzed.According to the research results,the division of protection units is determined and protection strategies are proposed.The main results are as follows:1)Analysis based on chloroplast DNA sequence:The length of chloroplast DNA（ndhF,rpl32,trnl-uag and CCSA and their spacing regions）was 5191bp after splicing,37 sites of variation and 16 haplotypes were detected.At the species level,the genetic diversity of C.perpetua was higher（h=0.903,π=0.00069）.At the population level,there is only one haplotype in 3 wild populations and 2 transplanted populations,and 7 transplanted populations contain multiple haplotypes.The haplotype Network was emittance,and the mismatch distribution showed a single peak.And haplotype H1 in the haplotype Network graph is located in the center of the Network graph and has the highest frequency,suggesting that it is the ancestor haplotype.AMOVA analysis showed that the variation mainly occurred between populations（74.31%）.All parameters of population in concentrated distribution area are higher than those of geographically isolated population.Mantel test showed that genetic distance was significantly correlated with geographical distance.Geographical isolation is the main cause of genetic differentiation.2)Data analysis based on microsatellite（SSR）:Ten pairs of microsatellite primers were applied to 351 samples of 12 species of C.perpetua,the average number of alleles（N_a）was6.133,the average number of available alleles（N_e）was 3.386,and the average observed heterozygosity（H_o）and expected heterozygosity（H_e）were 0.611 and 0.636,respectively.The results showed that the genetic diversity of WP population was the highest（N_a=7.5,H_o=0.63）.The genetic diversity of QN population was the lowest（N_a=4.0,H_o=0.513）.Genetic variation was mainly from within the population（86.91%）.The fixed index F is between-0.083 and 0.181.All parameters of population in concentrated distribution area are higher than those of geographically isolated population.The genetic differentiation level of C.perpetua is relatively low,the genetic differentiation coefficient(F_st)is between 0.011 and 0.11,the gene flow is relatively high,the gene flow among various populations is more than 1,and the genetic variation mainly comes from within the population（92.13%）.The STRUCTURE results show that K=6 is the best grouping,three wild populations and one geographically isolated transplanting population are grouped independently,and the transplanting populations in other villagers’homes are mixed with each other.The results showed that there was a certain genetic differentiation between wild populations,and the transplanted populations were a collection of natural populations from different locations.3)Based on whole genome sequencing of chloroplast:The whole genome of the chloroplast of C.perpetua was sequenced by Illuminad pair-end sequencing method.The results show that:The complete chloroplast genome length of Camellia perpetua is 156.804bp.It has a typical tetrad structure,in which the length of the reversed repeated sequence region（IRs）is 25.996 bp,and the length of the large single-copy sequence region（LSC）and small single-copy sequence region（SSC）is 86.570 and 18.242 bp.A total of 122 genes were annotated,including 86 protein-coding genes,28 tRNA genes and 8 rRNA genes.The GC content of the complete chloroplast genome sequence of C.perpetua was 37.32%.4)Propose protection strategies:According to the research results of genetic diversity and genetic structure of C.perpetua,propose targeted protection strategies for C.perpetua.On-site protection:3 wild populations are divided into 3 protection units for on-site protection;Ex-situ conservation:villagers transplant their families.All populations have high diversity and similar genetic structure.According to the actual situation,one population should be selected to move into the germplasm resources bank or transplanted back to the nearby natural habitat to protect its germplasm resources.