Abstract:

Sixty core EST-SSR primers, among which 59 were newly developed from the ESTs of tea plant, were selected and used to analyze genetic diversity and genetic structure of 51 landraces of tea (Camellia sinensis and C. sinensis var. pubilimba) distributed in Guangxi, China. A dendrogram based on genetic distance was constructed from software PowerMarker 3.25 using Neighbor-Joining clustering method. Two hundred and thirty-two alleles were amplified, and the number of alleles per primer ranged from 2 to 7, with an average of 3.88. The observed heterozygosity (H_</em>o) ranged from 0.02 to 0.92 but expected heterozygosity (H_</em>e) varied from 0.13 to 0.73, with average of 0.37 and 0.47, respectively. The average polymorphism information content (PIC) was 0.41. The genetic similarity coefficient among eight different regions was from 0.83 to 0.94, indicating there were close relationships among tea landraces in the different regions. Most of the diversity (98%) was found within populations, only 2% was between populations of C. sinensis and C. sinensis var. pubilimba. It was suggested that serious inbreeding occurred within the groups as shown by the coefficient of inbreeding (F=0.21). The 51 landraces from the different regions were grouped into three. Most tea landraces from Guilin, Laibin and Hezhou, and all from Qinzhou and Wuzhou were clustered into group Ⅰ of the dendrogram, while those from Chongzuo, Fangchenggang and Nanning were assigned into group Ⅲ. Other landraces were assigned into group Ⅱ. The results from Neighbor-Joining clustering method agreed with that from the model-based analysis of genetic structure.is

Key words: Camellia sinensis, Camellia sinensis var. pubilimba, genetic diversity, genetic structure, EST-SSR