| Tea plant is one of the important economic perennial crops and Yunnan province is the origin center of the world tea plant where has the extremely rich tea germplasm resources.To better protect the tea resources,genetic diversity of wild ancient tea and cultivated tea in Zhenyuan county was analyzed by EST-SSR markers.In this way,tea plant resources can be better used.On the other hand,we can provide the theoretical basis and practical basis on selection of hybrid parents in breeding,breed improvement and genetic resource conservation.The main achievements are as following:1.The genetic diversity and genetic structure of 7 wild tea populations at different altitudes in Qianjiazhai were studied by EST-SSR markers.At the species level,Observed number of alleles(Na),Shannon information index(I)and Nei's gene diversity(h)were 6.0000,1.3257 and 0.6603,respectively,indicating this species has high genetic diversity at species level.Along altitudinal gradients,the genetic diversity among population of wild tea was difference and showed low-high-low distribution.The genetic diversity of population at altitude 2100 m was much higher than that of other populations.AMOVA analysis showed that only 16.32% of the total genetic variation occurred among populations,whereas 83.68% of the variance was within populations,which was in line with the coefficient of genetic differentiation(Fst = 0.1194).And the gene flow Nm was 1.8431.The genetic diversity of wild ancient tea in Qianjiazhai was abundant and showed it's highest value in the population of 2100 m altitude.The genetic differentiation was weak and gene flow was not the main factor that causing genetic differentiation among populations.The existing genetic pattern of wild ancient tea was determined by it's genetic characteristics and the different elevation habitat heterogeneity.2.The genetic diversity and genetic structure of cultivated tea populations at different ages in ancient tea garden of Li village were studied by EST-SSR markers.At the species level,Observed number of alleles(Na),Shannon information index(I)and Nei's gene diversity(h)were 9.2000,1.7971 and 0.7827,respectively,indicating this species has rich genetic diversity at species level.What's more,it has not resulted in the loss of genetic diversity in the long-term cultivation and domestication.The genetic diversity of cultivated tea plants in different ages was Age2> Age1> Age3.The gene flow(Nm)and population differentiation coefficient(Fst)among cultivated tea plant populations were 5.1515 and 0.0463 respectively,which showed that there was no differentiation among the populations of different age classes,and the gene flow was very rich.The results showed that Nei's genetic identity between Age1 population and Age2 population was 0.8935.The lowest Nei's genetic identity that was 0.7181 appeared between the Age1 and Age3 populations.3.Through comparative study on genetic diversity of wild tea plants in Qianjiazhai and cultivated tea plants in Li village,we found that the number of Observed number of alleles(Na),Effetive number of alleles(Ne),Shannon information index(I)and Nei's gene diversity(h)of wild tea plant were lower than those of cultivated tea plant,which were 34.8%,35.4%,26.2% and 15.6% respectively.It showed that the genetic diversity of cultivated tea plant was higher than that of the wild tea plant.On the other hand,the frequency of gene exchange of cultivated tea plant was higher than that of wild tea plant.The results showed that Nei's genetic identity between wild tea plant and cultivated tea plant was 0.4572,which indicated that their genetic structure has a great difference. |
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