Identification of PAL genes related to anthocyanin synthesis in tea plants and its correlation with anthocyanin content

The phenylalanine ammonia-lyase (PAL) gene family in tea plants (Camellia sinensis L.) encodes the enzyme that catalyzes the first reaction of the phenylpropane metabolic pathway. The present study aimed to characterize the PAL genes in tea plants, and get better insights on the CsPALs in anthocyanins accumulation. Seven CsPAL genes were identified and characterized in tea plants by bioinformatics analysis. Systematic analysis of CsPALs was conducted for its phylogenetic relationship, gene structure, chromosomal location, and protein conserved motifs based on tea plant genome. The cis-elements of CsPALs were responsive to light, abiotic stress, hormone, and MYB-binding site. Furthermore, tissue-specific expression analysis showed that CsPAL4 was expressed preferentially in young leaves and buds. Correlation analysis was performed in purple-leaf tea with anthocyanin components, and it was suggested that CsPAL4 was closely related with different anthocyanin accumulated, especially with cyanidin 3-O-galactoside, cyanidin 3-O-glucoside, and delphinidin 3-O-glucoside. Additionally, the putative upstream regulation factors CsMYBs (CsMYB59, CsARR1, CsSRM1, CsMYB101, and CsMYB52) and CsbHLHs (CsbHLH104, CsbHLH3, CsbIM1, CsTCP14, and CsPIF4) could bind to the promoter of CsPALs, thereby activating its transcription. This study provides a theoretical basis for further research to elucidate the functions of the CsPAL genes.