Studies On Conservation Genetics Of Camellia Indochinensis

Camellia indochinensis Merr belongs to Camellia（Theaceae）,with mainly distributed in Ningming,Longzhou,Chongzuo and Fusui southern Guangxi,China.We collected a total of277 individuals from 10 natural populations.Here,we evaluated genetic diversity and population structure of Camellia indochinensis,using simple sequence repeat（SSR）and chloroplast DNA（cpDNA）sequence.According to the research results,protection strategies are proposed.The main results were as follows:1)The aligned cpDNA sequences were 5192 bp in length and contain 15 variable sites.For the 11 haplotypes detected from 10 natural populations of 277 individuals,the C.indochinensis had a higher genetic diversity in species level（cpDNA,Hd=0.876,π=0.00056）.But in population level,the C.indochinensis had a low genetic diversity.The DG population had three haplotypes and no share with other populations,and JB population had two private haplotypes,while the remaining ones were of private haplotypes.Haplotype H4 was found in regions LJ and LR populations,and haplotype H9 was found in regions LQ and LW populations.The SSR markers also expressed higher level of genetic diversity from C.indochinensis populations.161 alleles at 10 SSR loci were revealed across 277 individuals from 10 wild populations,with an average of 16.1 per locus.In the species levels,the average number of alleles（Na）of the simple sequence repeat（SSR）marker was 7.12,and it ranged from 5.500 to8.900,and the average number of alleles（Ne）was 3.126 to 4.809,with an average of 4.073.The observed heterozygosity（Ho）varied from 0.527 to 0.776 and average 0.686,while the effective heterozygosity（He）ranged from 0.634 to 0.754 and average 0.693.2)Based on cpDNA,Analysis of molecular variance（AMOVA）revealed genetic variation among population was 92.10%,genetic variation within population was 7.9%.Based on SSR data,the genetic differentiation coefficient F_ST values ranged from 0.052 to 0.220,with the average genetic differentiation coefficient(F_ST)was 0.127.Among them,the F_ST was between0.05 and 0.15 in thirty-three groups,and the F_ST value of twelve groups was between 0.15 and0.25,indicating a moderate level of genetic differentiation among wild C.indochinensis populations.The gene flow Nm values among population varied from 0.885 to 4.540,with an average value of 1.94,revealing more gene communication between populations.Analysis of molecular variance（AMOVA）showed that the percentage variation among populations was11.15%,and the percentage variation within population was 88.85%,which meant that within population variance was the main resource of genetic variation of C.indochinensis.The graph of?K corresponds to K value showed that there were two good peaks,K=2 and K=9,respectively,but it is considered the grouping of K=9 was reasonable.STRUCTURE cluster analysis showed that the ten population has been more carefully divided when K=9,and the ten populations were divided into 9 groups.HLZ and JM populations formed a group,but the other populations were each a separate group.Mantel test showed that there was no significant correlation between genetic and geographic distance（R²=0.0537,p>0.05）.In addition,the present distribution range of C.indochinensis had not experienced ranged expansion by the haplotype analysis of mismatch distribution and neutral test.BOTTLENECK analysis revealed that 10 C.indochinensis populations had not experienced bottlenecks.3)In addition,we further sequenced and assembled the complete chloroplast genome sequence of C.indochinensis.In this study,Illumina sequencing method was used to establish its complete chloroplast（cp）genome.The total chloroplast genomes of is 156571 bp in length with 37.3%GC contents,including a large single-copy（LSC）region of 86246 bp and small single-copy（SSC）18219 bp,and a pair of invert repeats（IR）regions of 26053 bp.The chloroplast genome contains 121 genes,comprised of 85 protein-coding genes,28 tRNA genes,and 8 rRNA genes.4)In summary this study reveal that C.indochinensis had high level of genetic diversity.STRUCTURE cluster analysis showed that ten populations should be split into two genetic groups 9 group,both HLZ and JM populations were assigned to together.All populations should be protected as much as possible.The populations of DG and JM outside the protected area have been seriously damaged,so the effective protection should be performed.