Studies On The Genetic Diversity Of Traditional Tea Germplasm In China As Well As The Influence Of Artificial Selection

Tea plant is a kind of self-incompatibility plant species originated from southwest China, where tea genetic resources are abundant. In factor, these resources have already become a good foundation for tea germplasm collection and breeding. Meanwhile, the traditional cultivars with local characteristics are important for the excavation, utilization and protection of these resources. Thus, it is necessary to investigate the genetic diversity of these cultivars to guide tea breeding in future.In this study, EST-SSR markers were utilized to evaluate the genetic diversity and effects of artificial selection on traditional tea cultivars in China. Firstly, 64 cultivars from six important tea product provinces were analyzed and the genetic diversity of each province was compared. Secondly, the genetic diversities of 83 traditional tea cultivars were also investigated by two kinds of markers: EST-SSR markers and morphological markers. Finally, the effects of artificial selection on the genetic diversity of Fujian tea cultivars were also studied. The main results of this research are as follows:1. EST-SSR analysis of the traditional tea cultivars from six provinces in the south of Yangtze River.1)50 pairs of EST-SSR primers were selected for analyzing the genetic diversity of 64 traditional tea cultivars from six provinces in the south of Yangtze River. The average polymorphism information content (PIC), Nei's value and Shannon index of loci were 0.50, 0.55 and 1.01, respectively, indicating a high level of genetic diversity in this area.2)The diversity of 64 traditional tea cultivars from six provinces was analyzed. The order of provinces with the level of genetic diversity ranging from high to low was Fujian>Zhejiang>Hunan>Jiangxi>Hubei>Anhui.2. The genetic diversity of traditional tea cultivars in China based on EST-SSR markers and morphological analysis.1)The genetic diversity of 83 traditional tea cultivars was studied using 50 pairs of EST-SSR primers. A total of 206 putative alleles and 423 genotypes were generated. The average PIC and Shannon index (I) were 0.50 and 1.02, respectively, which showed a high genetic diversity in rthese cultivars.2)The morphological diversities of tea leaves were also studied. The results showed a certain degree of similarity among cultivars. For example, 97.6% of the cultivars had small or medium size leaves and 73.5% had slightly rugose in leaf upper surface. On the other hand, high diversities could be observed in characters like ovate, elliptic, oblong and lanceolate in leaf shape. High genetic diversities of these cultivars could be found by both EST-SSR markers and morphological markers.3. The effects of artificial selection on tea germplasm in Fujian province.36 pairs of EST-SSR primers were used to analyze the genetic diversity of 60 tea varieties from Fujian. A total of 165 polymorphic bands and 343 genotypes with a PIC of 0.54 were generated. The results of dendrogram and structure analysis showed that those tea cultivars could be majorly divided into two groups. One includes 15 tea varieties seldom applied in tea production, and the other contains varieties confirmed or registered by national or provincial variety registration organizations and popularly in tea production for their good quality. The result also showed that the genetic diversity of those unregistered traditional varieties was the highest, whilst the registered traditional varieties was the lowest, suggesting the varieties widely used in tea production had lower polymorphism and less genetic diversity, which might be due tothe same or similar selection criterion or target in artificial selection or breeding programs.