Assessment of Genetic Diversity and Relationship of Tea Germplasm in Yunnan as Revealed by ISSR Markers

The relationship and the genetic diversity of 134 accessions of the Yunnan tea [Damellia sinensis (L.) O. Kuntze] germplasm belonging to 8 species were analyzed to provide guidance for breeding of tea tree. Using 18 inter-simple sequence repeats (ISSR) primers, a total of 475 fragments were amplified, of which 470 bands were polymorphic. The genetic similarity (GS) among the accessions tested ranged from 0.445 to 0.819 with an average of 0.512. These results indicated a rich diversity in the tested genetic germplasm of tea. Based on the cluster analysis using unweighted pair-group method with arithmetic average (UPGMA), all the tea accessions fell into 3 groups with no obviously geographical character. The principal component analysis (PCA) supported the clustering result, but relationships among accessions were more explicit in the PCA graph than the UPGMA dendrogram. The genetic variation among species was small, as the average GS among species was 0.92, ranging from 0.850 to 0.987.

摘 要以8个种群134份云南茶树资源为材料, 应用ISSR标记方法, 进行了遗传多样性与亲缘关系分析。结果表明, 18个多态性ISSR引物对全部试验材料进行PCR扩增, 共获得475条稳定的谱带, 其中多态性谱带470条(占98.9%), 说明遗传多样性丰富。应用Nei-Li相似系数法估算了134个材料间的相似系数为0.445∼0.819, 平均为0.512, 说明茶树资源间的遗传基础较宽。对134份茶树资源的分子系统聚类分析(UPGMA)将资源分为3大组, 聚类结果与地理距离没有明显的相关性; 主成分分析(PCA)表明主成分分析的结果与系统聚类基本一致, 但是主成分分析更加直观清晰地显示各个材料间的亲缘关系。大厂茶等8个种群间的遗传相似系数介于0.850∼0.987间, 平均为0.92, 表明不同种群间的遗传差异较小。