Genetic diversity in tea (Camellia sinensis) germplasms as revealed by ISSR markers

To efficiently utilize, maintain and assess tea [Camellia sinensis (L.) O. Kuntze] germplasms, inter-simple sequence repeats (ISSR) were used to determine genetic relationships among 100 location tea germplasms. Eighteen ISSR primers generated 472 polymorphic bands (99.4% of the total) and distinguished the 100 tea germplasms. The genetic distance among the genotypes ranged from 0.167 to 0.797, with a mean of 0.501, whereas the mean Nei's gene diversity (H) and the overall mean Shannon's Information index (1) were 0.396 and 0.578, respectively, indicating a wide gene pool. The Jaccard similarity co-efficients among genotypes ranged from 0.262 to 0.810. The 100 germplasms were divided into 5 groups on the basis of unweighed pair-group method with arithmetic averages analysis (UPGMA). The largest group consisted of 30 germplasm. The other 4 groups included 67 germplasms except 3 non-clustered germplasms. The phylogenetic groups generated by ISSR markers did not correspond to their geographical origin. Principal Component analysis (PCA) of ISSR data supported UPGMA clustering results. The ISSR can be useful as DNA-based molecular markers for studying genetic diversity, phylogenetic relationships, identification of tea germplasms or cultivars, and genetic improvement and selection of crossbred parents in tea breeding programmes.