Effects of light and darkness on polyphenol distribution in the tea plant (Camellia sinensis L.).

1. Flavonoid synthesis was able to proceed in darkness in young shoots and seedlings of the tea plant, but was increased by light. 2. The initial effect of darkness was to inhibit synthesis of the A ring or its linkage to the phenylpropane moiety of the flavonoid, but later the hydroxylation state of the flavanols was affected, leading to smaller proportions of gallocatechins and of complex leucoanthocyanins. 3. The esterification of catechins with gallic acid was less affected, so that the ratio of catechin gallates to simple catechins also increased. 4. The flavylogen content of darkened stems, especially in seedlings, was much less decreased than that of leaves; however, a short subsequent light-treatment caused an increase in polymerization.