Caffeine Metabolism in High and Low Caffeine Containing Cultivars of Camellia sinensis
2014
Ashihara, Hiroshi | Shimizu, Hisayo | Takeda, Yoshiyuki | Suzuki, Takeo | Gillies, Fiona M. | Crozier, Alan
The metabolism of [8-¹⁴C ]adenine and [2-¹⁴C]caffeine was examined in leaf segments from flush shoots of tea cultivars with high and low caffeine content. The caffeine biosynthesis pathway from AMP via theobromine was operative in both high and low caffeine containing cultivars. There was a m ore rapid rate of caffeine biosynthesis from [8-¹⁴C ]adenine in the high caffeine cultivars while the rate of degradation of both adenine nucleotides and caffeine into CO₂ was greatest in cultivars with a low endogenous caffeine content. Cell-free p reparations from tea shoots contained an N-methyltransferase, that is a keyenzyme in the caffeine biosynthesis pathway; more in-vitro activity was detected in preparations from high caffeine containing cultivars. The data obtained suggest that the high caffeine containing cultivars have a more rapid rate of caffeine biosynthesis and a slower rate of caffeine catabolism than cultivars with a low endogenous caffeine content
显示更多 [+] 显示较少 [-]