中文摘要：

Caffeine,theobromine and theophylline are the major purine alkaloids found in Camellia sinensis.Theacrine was detected in a special Chinese tea plant named kucha(Camellia kucha).With tracer experiments,the metabolism pathway of these purine alkaloids has mostly been explored.The isolation and cloning of the genes encoding enzymes in the related pathway made it possible to develop methods to control caffeine level in tea products via transgenic technique.Further study on the kucha species would be helpful to obtain materials for processing naturally caffeine-less tea.However,there is still a long way to go in this direction such as sensory improvement of products prepared using leaves of kucha.

英文摘要：

Caffeine,theobromine and theophylline are the major purine alkaloids found in Camellia sinensis.Theacrine was detected in a special Chinese tea plant named kucha （Camellia kucha）.With tracer experiments,the metabolism pathway of these purine alkaloids has mostly been explored.The isolation and cloning of the genes encoding enzymes in the related pathway made it possible to develop methods to control caffeine level in tea products via transgenic technique.Further study on the kucha species would be helpful to obtain materials for processing naturally caffeine-less tea.However,there is still a long way to go in this direction such as sensory improvement of products prepared using leaves of kucha.