云南茶树资源遗传多样性与亲缘关系的ISSR分析

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%)，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。

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

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 provide 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 cluster 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 supported UPGMA clustering result, but showed more explicit relationships among the test accessions with different lays, orientationsand positions. The GS among 8 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.