Objective Genetic characteristics of PAL, C4H, and 4CL family members in tea were studied to examine the connection between these genes and abundance of phenylethanol primrose glycoside (PPG) in the plant.

Method Using bioinformatics and transcriptome sequencing techniques, the distribution, physicochemical properties, gene structure, phylogenetic relationships, promoter cis-acting elements, and expression characteristics of CsPAL, CsC4H, and Cs4CLs in the genome of tea plants were analyzed. Expressions of these genes in the shoots of low- and high-glycoside teas, which differed significantly in PPG content, were compared.

Result Seven CsPALs, 4 CsC4Hs, and 4 Cs4CLs were found in 9 chromosomes of tea plants. All CsPALs had only one intron, while all CsC4Hs other than CsC4H4 had two and all Cs4CLs had multiple introns. Phylogenetically, they closely related to PAL, C4H, and 4CL of Populus trichocarpa with a similarity in structure and conserved motifs. The promoter regions of CsPALs, CsC4Hs, and Cs4CLs contained elements responding to stresses, growth, development, and presence of hormones. The tissue specific gene expression could be induced by exposure to hormones, low temperature, drought, or high salinity. Significantly differentiated, CsPAL7 was highly expressed in the high-glycoside teas than the low-glycoside teas, but CsC4H4 and Cs4CL3 were the opposite. The varied expression patterns might indicate different roles these families played in the PPG formation in tea plants.

Conclusion The information obtained on CsPALs, CsC4Hs, and Cs4CLs would be of value for the understanding of the biological functions of these genes and breeding new tea varieties.