Study On Genetic Diversity Of Tea By AFLP Technology

Cross-breeding is the main way of tea breeding currently in China. At present, tea scientists choose hybrid-parents still based on morphological, physiological and biochemical indicators which are the results of gene expression that greatly influenced by the environment, age and the changes of season.However,those germplasms which have great differences in these indicators may only have a little difference in genome. So it makes cross-breeding blindness, poor targeted, and low efficiency. In this paper, genetic diversity and distance of 43 cultivars fit for green tea and 45 black tea cultivars were evaluated and analyzed by AFLP molecular marker technique, which provide a lot of theoretical foundation for the selection of good germplasm before coss-breeding. The main conclusions were as follows:1. This study using five pairs of primer combinations E41M42, E41M47, E41M55, E37M32 and E37M47 to study 43 cultivars fit for green tea and 45 black tea cultivars' genetic diversity, the clear DNA fingerprinting figures were successfully obtained. Five pairs of primers amplified 382 bands including 342 diversity bands in green tea cultivars ,the average per primer amplification was 76.4 bands, the average diversity bands per primer was 68.4, and the average frequency of polymorphism was 89.53%; At the same time, 45 black tea samples amplified 486 bands with 429 polymorphism band, the average bands per primer was 97.2,average polymorphism bands 85.8, average frequency of polymorphism 88.27 percent.2. Respectively using DPS9.5 caculating the genetic distance. 43 testing green tea materials' genetic distance between the range of 0.19 and 0.49, with an average of 0.34. And the genetic distance between Baihaozao and Donghuzao is 0.19 as well as the lowest, and among Xiangfeicui,Longnu,Yuhangfuyun and Junshan green tea, Longnu,Heiye shuixian,Echa-1,and Junshanyingzhen-1, Wanlaichun and Longnu, Heiyeshuixian and Chunbonu, the genetic distance is 0.49,the highest ; The genetic distance of black tea is between 0.16 and 0.49, with an average of 0.33.The highest distance were pairs of Wulinghong,Changyebaihao,Zixuan96-1,Chuyeqi and 9809, Liancha-4 and Sichuandashucha,was 0.49, and the lowest was between An-86 and Liancha-4, was 0.16.3. Using DPS9.5 data processing software with UPGMA method respectively constructed the dendrogam map. 43 green tea can be divided into six groups according to the combination line 0.34;According to the average genetic distance of 0.33, 45 tea varieties can also be divided into five groups, groups I, II and III has only one species each, they are 9809, Sichuan big tea tree and Fuyun-6, group IV composed by Qian Mei-419 and Yuankang-43, the remaining 40 species belonging to groups VI.4. Through the analization of the genetic disance between the varities, 15 combinization of hybrid parents have been chosen from the 43 samples suitable for processing green tea cultivars. At the mean time,3 combinization has been chosen from the 45 samples suitable for processing black tea cultivars.5. Through the analization of genetic map, a specific band of primer E37M47's fmgerpring map was found which may tell the difference between green tea and black tea cultivars' at the early time in cross-breeding. So primer E37M47 combinization can be used to study the new breeding varieties' tea suitable processing system of early identification.