Expression of basic genes involved in tea polyphenol synthesis in relation to accumulation of catechins and total tea polyphenols

Catechins, a group of polyphenolic compounds in the green leaf of tea [ Camellia sinensis (L.) O. Kuntze], are major components conferring quality attributes and health benefits on processed tea. Expression patterns of the basic genes related to accumulation of the catechins and total polyphenols at different stages of tea leaf development and their relationship with catechin concentration were investigated by reverse transcriptase polymerase chain reaction and high‐performance liquid chromatographic methods. The results showed that the concentration of total catechins and polyphenols in leaves at different stages of development declined with age of the leaf but changes of the individual catechins varied, with a general decrease in catechin gallate and epigallocatechin gallate and increase in epigallocatechin and epicatechin gallate. Genes of phenylalanine ammonium lyase (PAL), dihydroflavonol reductase (DFR) and three chalcone synthase genes (CHS1, CHS2, CHS3) were highly expressed in bud, first leaf and second leaf but were barely detected in mature leaves. The expression of DFR, a downstream gene in the catechin biosynthesis pathway, was closely related to the concentration of total catechins and polyphenols in various stages of leaf development. Copyright © 2005 Society of Chemical Industry