Abstract:

Tea is an important beverage crop in China. In recent years many clonal tea cultivars have been developed and widely replaced the diverse traditional tea population. Our knowledge on genetic diversity and relationship of these clonal tea cultivars is critical to guide tea breeding, but still limited. In this study, the genetic diversity and relationship of 36 clonal tea cultivars which mainly cultivated in China were analyzed with ISSR markers. Based on 20 ISSR primers, total 368 bands were generated, of which 367 (99.7%) were polymorphic. The average polymorphism information content (PIC) was 0.90, Nei’s gene diversity (H) and Shannon’s information index (I) were 0.23 and 0.38, respectively. Diversity of clonal cultivars within tea area was lower than that of in whole nation. The levels of diversity in Tea Area of Jiangnan and South China were higher than those of Southwest China. Analysis of molecular variance (AMOVA) showed that variance component among cultivars (94.4%) was far higher than that among regions (5.6%). The genetic similarity among all the tested clonal cultivars ranged from 0.58 to 0.84, averaging 0.69, which indicated that the genetic basis was relatively narrow. The cluster analysis based on ISSR markers revealed that cultivar “Jinxuan” from Chinese Taiwan was of the farthest distance with others from Chinese mainland in the dendrogram. Thirty-five clonal cultivars from Chinese mainland were clustered into a major group, and they could be further classified into three sub-groups except cultivar “Yihongzao”. The genetic relationship of all 36 tea cultivars revealed by the ISSR dendrogram would be of great help to accurately select the parents in tea breeding programs.

Key words: Tea, Cultivar, ISSR, Genetic diversity, Genetic relationship