Genome-Wide Identification of ABCC Gene Subfamily Members and Functional Analysis of CsABCC11 in Camellia sinensis

The ATP-binding cassette (ABC) transporter is a gene superfamily in plants. ATP-binding cassette subfamily C (ABCC) protein is a multidrug resistance-associated (MRP) transporter. They play various roles in plant growth, development, and secondary metabolite transport. However, there are few studies on ABCC transporters in tea plants. In this study, genome-wide association study (GWAS) analysis of epigallocatechin gallate (EGCG) content in 108 strains of Kingbird revealed that CsABCCs may be involved in EGCG transport. We identified 25 CsABCC genes at the genomic level of the tea plant, their phylogenetic tree, gene structure, targeted miRNA and other bioinformatics were analyzed. The expression patterns of CsABCCs in eight different tissues and abiotic stress indicate that they have potential roles in regulating the growth, development, and defense of tea plants. The correlation analysis revealed that the expression of the CsABCC11 gene was closely related to the EGCG content in tea buds of 108 strains of the Kingbird, and the subcellular localization experiments in tobacco showed that CsABCC11 protein was localized on the plasma membrane. The virus-induced gene silencing (VIGS) strategy in tea plants further verified that CsABCC11 was involved in EGCG accumulation. Our study laid a foundation for studying the biological function of CsABCC and provided a new candidate molecular marker gene for further EGCG-related variety breeding, which will be of great interest to breeders.