Genetic Diversity and Relationship of Tea Germplasm in Yunnan Revealed by ISSR Analysis

Abstract

Tea is an important beverage crop in the world. Yunnan region in China is the origin center of tea plants. Our knowledge on genetic diversity and relationship of tea germplasm in Yunnan province is critical to guide tea breeding. In order to pro-vide theoretical information for using tea germplasm in tea breeding, we investigated the relationship and genetic diversity of the tea germplasm in Yunnan province. Eight species, including 134 tea varieties were used to detect the genetic variation by inter-simple sequence repeats (ISSR) analysis. The result showed that 475 DNA fragments among all 134 tea accessions were amplified, using 18 reliable ISSR primers, among which 470 DNA bands were polymorphic (PPB=98.9%). This indicated that a great amount of genetic polymorphism exists among tea germplasm tested. The genetic similarity (GS) among the tested genotypes ranged from 0.445 to 0.819, with an average of 0.512, indicating a wide gene pool among tea varieties in Yunnan. The clus-ter analysis presented that these resources were divided into three main groups using the unweighted pair-group method with arithmetic average (UPGMA) based on ISSR molecular marker data, but the dendrogram did not indicate clear division among tested varieties based on their geographical origin. Principal Component analysis (PCA) for ISSR data showed that PCA sup-ported UPGMA clustering result, but showed more explicit relationships among the test accessions with different lays, orientations and positions. The GS among eight populations ranged from 0.850 to 0.987, with an average of 0.92, indicating that there existed a small variation of genetic diversity among different population. The findings of this research would be favorable for the further practice, such as tea breeding, the molecular genetic linkage mapping and the DNA fingerprint building of tea germplasm.