Effect of shade treatment on biosynthesis of catechins in tea plants

When tea plants were shaded with black lawn cloth for severaldays in the field, the accumulations of (—)-epicatechin,(—)-epicatechin-3-gallate, (—)-epigallocatechinand (—)-epigallocatechin-3-gallate decreased in newlydeveloping tea shoots. Radioactive tracer studies showed thatthe conversions of glucose-U-¹⁴C, shikimic acid-G-¹⁴C and phenylalanine-U-¹⁴Cinto (—)-epicatechin and (—)-epigallocatechin moietieswere depressed by the shade treatment for tea plants but theincorporation of trans-cinnamic acid-3-¹⁴C was not affected.The treatment was found to have no significant effect on theactivities of phospho-2-keto-3-deoxy-heptonate. aldolase (EC.4.1.2.15 EC] ), 3-dehydroquinate synthase (EC. 4.6.1.3 EC] ), 3-dehydroquinatedehydratase (EC. 4.2.1.10 EC] ), shikimate dehydrogenase (EC. 1.1.1.25 EC] )and trans-cinnamate 4-monooxygenase (EC. 1.14.13.11 EC] ) in theshoots, whereas the activity of phenylalanine ammonia-lyase(EC. 4.3.1.5 EC] ) clearly decreased. (Received March 17, 1980; )