Genetic Diversity And Population Structure Of Tea Plants In Lincang Of Yunnan Province

Genetic diversity is considered to be the baseline of biodiversity.The more genetic diversity or variability within a species,the greater ability to adapt the changing environmental condition.Genetic diversity research can provide a basis for the researches of species origin and domestication,genetic breeding and improvement,germplasm characterization,utilization and protection.City of Lincang is the second largest tea-producing area in Yunnan,wherein it hosts the most diverse number of species and varieties of Sect.Thea in the Camellia genus.Wild and cultivated Camellia taliensis,and C.sinensis var.assamica is wildly distributed in Lincang.In this study,a chloroplast intergenic spacer rpl32-trnL sequence and 30 nuclear SSR molecular markers were employed to study genetic diversity and genetic structure of tea plant in Lincang.The main results are listed as follows:1.Based on the chloroplast intergenic spacer rpl32-trn L sequence,7 haplotypes were identified based on nucleotide variation.The total haplotype diversity index and nucleotide diversity index were0.6820 and 0.00475.At populations level,XG(H_d=0.4340,?=0.00510)and NH(H_d=0.6800,?=0.00440)contained a higher level of genetic diversity.DXS contained a lowest haplotype diversity and nucleotide diversity which only has one haplotype distribution.H6 and H7 as the private haplotypes were fixed in XG population.AMOVA analysis revealed that the proportion reside of chloroplast variation among populations(56.95%)was slightly higher than but close to that within populations(43.05%).NCA analysis indicated that the restricted gene flow with isolation by distance was the major causes of the population's genetic structure.2.Based on the SSR markers,tea plant in Lincang contained a higher level of genetic diversity.BYS(I=1.245,H_o=0.547,H_e=0.614)and XZQ(I=1.132,H_o=0.429,H_e=0.557)population own the highest genetic diversity,we assumed that the gene flow between C.taliensis and C.sinensis var.assamica could be increase the genetic diversity by accumulating hereditary changes.Compared with other populations,BD(I=0.706,H_o=0.374,H_e=0.399)population own the lowest genetic diversity.AMOVA analysis showed that the genetic variation mainly existed within population,representing of74%of the total variation.Then based on the bottleneck test analysis,indicated tea plant in Lincang possibility experienced bottleneck effect during its evolution.According to Ennos'formula,pollen flow was 4.97 times bigger than seed flow.Structure analysis showed that 3 clusters formed the current genetic structure of tea plant in Lincang.BYS population contained a special cluster which genetic background is unknown.3.cpDNA intergenetic regions rpl32-trnL and 30 SSR markers were used to study 130 individuals from 7 subpopulations.A high level of genetic diversity were detected in HTZ(H_d=0.541,?=0.00510,I=1.127,H_o=0.656,H_e=0.590)subpopulation.BYZ(H_d=0.541,?=0.00510,I=0.421,H_o=0.582,H_e=0.315)subpopulation own the lowest genetic diversity.4 haplotypes were identified based on nucleotide variation,H4 is the unique haplotype for MKZ.BYZ contains only H3 and TZC contains only H1.AMOVA analysis showed that the genetic variation mainly existed within population,representing of 89.91%(cpDNA)and 77.78%(SSR)of the total variation.According to the cpDNA haplotype results,genetic differentiation among subpopulations was moderately,the gene flow(N_m)is2.16 which indicated that the gene flow between subpopulations is high.however,SSR revealed high genetic differentiation.Structure analysis showed that 2 clusters formed the current genetic structure of tea plant in Baiyingshan.But when the K to take 3,BYS showed a special genetic background.With the previous date analysis,we can exclude BYZ from C.sinensis var.sinensis.Based on cluster analysis combined to Structure,the classify has some rationality,but it still needs to be supplemented by molecular markers.