Studies on differentiation of Japanese tea cultivars (Camellia sinensis var. sinensis) acoording to the genetic diversity of phenylalanine ammonia-lyase

Phenylalanine ammonia-lyase (PAL) cDNA of tea was used in evaluating the genetic diversity of tea genetic resources and in determining the differentiation process of Japanese green tea cultivars. The PAL cDNA was also very useful for identifying interspecific hybrids between C.sinensis and C. japonica. PAL DNA diversity was found not only between C. sinensis var. sinensis and var. assamica, but among var. sinensis. Three multi-allelic fragments, A, B and D, were detectable by RFLP analysis using the PAL cDNA probe, and Japanese green tea cultivars were divided into 5 genotype groups: AA, AB, AD, BD and DD. Cultivars belonging to the BB type do not exist. Japanese green tea cultivars and local tea plants, including mountain tea, yama-cha, were analyzed to determine the process of differentiation of Japanese tea plants by using the PAL DNA markers, A, B and D. Since the genetic frequencies in yama-cha and local tea plants were also the same, these teas may have the same origin. A comparison of DNA diversity between Japanese and Korean-Chinese germplasm suggested that limited populations of tea from China have been introduced into Japan. Then, the limited populations were distributed within Japan and local varieties were formed in tea cultivated regions. 'Yabukita' which was selected from this population, is a leading variety. In green tea breeding, a change of selection from local variety populations to hybrids with 'Yabukita' influenced PAL genetic frequency among Japanese green tea cultivars. These results using PAL markers cleared the differentiation process of Japanese green tea cultivars and the information in this study will contribute to the breeding of new cultivars.