Characterization and Expression Profiling of Camellia sinensis Cinnamate 4-hydroxylase Genes in Phenylpropanoid Pathways.

Cinnamate 4-hydroxylase (C4H), a cytochrome P450-dependent monooxygenase, participates in the synthesis of numerous polyphenoid compounds, such as flavonoids and lignins. However, the gene number and function in tea plants are not clear. We screened all available transcriptome and genome databases of tea plants and three genes were identified and named , , and , respectively. Both and have 1518-bp open reading frames that encode 505-amino acid proteins. has a 1635-bp open reading frame that encodes a 544-amino acid protein. Enzymatic analysis of recombinant proteins expressed in yeast showed that the three enzymes catalyzed the formation of -coumaric acid (4-hydroxy -cinnamic acid) from -cinnamic acid. Quantitative real-time PCR (qRT-PCR) analysis showed that was highly expressed in the 4th leaf, was highly expressed in tender leaves, while was highly expressed in the young stems. The three were induced with varying degrees by abiotic stress treatments. These results suggest they may have different subcellular localization and different physiological functions.