CAFFEINE METABOLISM IN HIGH AND LOW CAFFEINE CONTAINING CULTIVARS OF CAMELLIA-SINENSIS

The metabolism of [8-C-14]adenine and [2-C-14]caffeine was examined in leaf segments from flush shoots of tea cultivars with high and low ca ffeine content. The caffeine biosynthesis pathway from AMP via theobro mine was operative in both high and low caffeine containing cultivars. There was a more rapid rate of caffeine biosynthesis from [8-C-14]ade nine in the high caffeine cultivars while the rate of degradation of b oth adenine nucleotides and caffeine into CO2 was greatest in cultivar s with a low endogenous caffeine content. Cell-free preparations from tea shoots contained an N-methyltransferase, that is a key enzyme in t he caffeine biosynthesis pathway; more irt-vitro activity was detected in preparations from high caffeine containing cultivars. The data obt ained suggest that the high caffeine containing cultivars have a more rapid rate of caffeine biosynthesis and a slower rate of caffeine cata bolism than cultivars with a low endogenous caffeine content.