Analysis On Genetic Diversity In Tea (Camellia Sinensis) And Genetic Linkage Map Construction

Both selection of parents before cross-fertilization to make great genetic differences and selection in progenies under guide of effective techniques are the two nuts during new tea variety breeding. They are the main purposes of conducting genetic diversity and constructing linkage map for tea (Camellia sinensis (L.) O. Kuntze). Research on genetic diversity and linkage map construction are great useful in enhancing breeding efficiency. There are several reports on genetic diversity and linkage map construction in tea nowaday. In this research we established a AFLP fingerprinting technique with silver staining, and used it to evaluate genetic diversity in Oolong tea germplasms, and compared the creditability on estimation of genetic diversity in tea with AFLP and ISSR markers. Furthermore, we estimate the genetic diversity in Chinese tea varieties for cultivation, probing into segregation made in backcross with ISSR and RAPD markers, and constructed a partial linkage map for tea. The main results were as follow:An AFLP fingerprinting technique for tea using silver staining method was optimized based on literatures. The result indicated the technique was stable and highly reproducible with distinct band patterns and low background. We concluded that three factors should be attentive for attaining a fine fingerprinting. They are DNA quality and its integrity, fully DNA digestion, and controls of temperature in surrounding during electrophoresis and silver staining.Genetic diversity in 45 Oolong germplasms from Fujian, Guangdong and Taiwan was evaluated by AFLP fingerprinting based on silver staining technique using 5 primer combinations. The 5 primer combinations generated 208 polymorphic bands. Estimated genetic diversity within the 45 germplasm was up to 0.311. Genetic diversity within Wuyu Mountain population was highest, while genetic diversity within Anxi population was higher than Guangdong and Taiwan populations and lowest within Taiwan population. A dendrogram generated by NT-SYS software indicated that the 45 Oolong tea germplasms could be divided as Wuyu type and Chaoan type. Genetic similarity determined by Popgene 32 software was highest between Anxi and Wuyu populations, and was lowest between Taiwan and Chaoan populations. It could be infered that Fujian Oolong tea germplasm originated from Wuyu Mountains.Genetic diversity in 59 tea germplasms in China for was evaluated by ISSR fingerprinting with 14 primers. The results indicated largest genetic distance was 0.77, and lowest 0.11. Fujian Oolong tea varieties was divided as single type by constructed genetic dendrogram with UPGMA method. Genetic diversity between Fujian, Zhejiang and Jiangxi population and Oolong tea germplasms from Fujian and Taiwan population was farthest, and Fujian, Zhejiang and Jiangxi population and Anhui, Hunan and Hubei population was lowest. Genetic diversity within Yunnan, Guizhou and Sichunpopulation was highest than Guangdong and Guangxi population, and lowest within Fujian, Zhejiang and Jiangxi population. It indicated that Fujian and Taiwan Oolong tea germplasms should be divided as single type indicate by genetic similarity analysis between populations. It could be inferred that Fujian and Taiwan Oolong tea germplasm had a unique origin.The consistency of genetic diversity analysis results attained by AFLP and ISSR markers was investigated. The results showed the AFLP marker had a higher efficient in polymorphic locus per amplification, while ISSR marker had a higher ratio of polymorphic locus, and higher estimation value on genetic diversity as well. The relative location for each variety in two dendrograms mostly was the same, but with a few exceptions. Mantel test for the similarity indicated two evolution trees were great significant correlated (r=0.811, p<0.0001). It could be inferred that the two molecular fingerprinting techniques both were suitable for tea genetic diversity research.The segregation mode for Fu Ding Da Bai Cha and its 94 BC1 progenies was investigated using RAPD and ISSR markers. Among 174 segregation loci, 102 loci were amplified by 14 ISSR primers, and 72 loci were amplified by 20 RAPD primers.The segregation of 90 loci, in which 63 were ISSR loci, were consistent with the expected 1:1 Mendelian ratio at 51.7% of loci. 36 loci were consistent with the expected 3:1 Mendelian ratio, and 48 loci were Segregation distortion. Linkage map for Fu Ding Da Bai Cha based on marker data from the BC1 population were generated with Mapmaker. The marker data assorted into 7 linkage groups.this map concluded 43 RAPD and 19 ISSR markers,covered 1180.9 cM distance. The average distance between markers was 20.1 cM. The largest linkage group was LG6,which included 18 markers, and its average distance was 15.7cM.