Genetic diversity of the contents of caffeine, catechins, and free amino acids in tea leaves collected from northern mountain areas of Vietnam

It is believed that the location of the origin of tea (Camellia sinensis (L.) O. Kuntze) is the border area of Vietnam, Laos, Thailand, Myanmar, and China. Therefore, research of the diversity of tea genetic resources in Vietnam is important for tea science. A collaborated mission to explore and collect tea genetic resources in Vietnam was conducted from 23 November to 14 December 2003. During this mission, we collected 135 tea shoot samples from the northern mountain areas of Vietnam. A11 of the collected tea plants were classified into Camellia sinensis var. assamica. Based on the differences of leaf morphology and quality of green tea, Vietnamese green tea plants are classified into two groups, Shan tea (large leaf and high quality) and Trungdu tea (small leaf and low quality). The green tea quality of Shan tea is superior to Trungdu tea, so, Vietnamese tea scientists are very interested in Shan tea. In the present study, the contents of caffeine, individual catechins, and free amino acids in collected Vietnamese tea shoot samples were analyzed by high-performance liquid chlomatogram (HPLC). Most Shan tea and Trungdu tea have high amounts of caffeine and catechins. However, some plants contained low amounts, such as green tea cultivars 'Yabukita' bred from C. sinensis var. sinensis. A few plants of Shan tea and Trungdu tea contained a high concentration (above 1.5% of dry leaf weight) of epigallocatechin 3-O-(3-O-methyl) gallate, which has an anti-allergic function. The composition ratio of catechins of Vietnamese tea shoot differed according to the point where it was collected. HPLC analysis results also suggested that Vietnamese tea has low contents of free amino acids and the composition ratio of free amino acids differed according to the point where it was collected. These results suggested Vietnamese tea genetic resources have high variations for the composition ratio of these three chemical components. Our results also suggested that the genetic resources of Trungdu tea are equal to Shan tea as important breeding materials of the functional tea components for human health benefit.