Genome-wide identification and expression pattern profiling of the ATP-binding cassette gene family in tea plant (Camellia sinensis)

The ATP-binding cassette (ABC) gene family is one of the largest and oldest protein families, consisting of ATP-driven transporters facilitating substrate transportation across cell membranes. However, little is known about the evolution and biological function of the ABC gene family in tea plants. In this study, we performed a genome-wide identification and expression analysis of genes encoding ABC transporter proteins in Camellia sinensis. Our analysis of 170 ABC genes revealed that CsABCs were unevenly distributed across 15 chromosomes, with an amino acid length ranging from 188 to 2489 aa, molecular weight ranging from 20.29 to 277.34 kDa, and an isoelectric point ranging from 4.89 to 10.63. Phylogenetic analysis showed that CsABCs were divided into eight subfamilies, among which the ABCG subfamily was the most abundant. Furthermore, the subcellular localization of CsABCs indicated that they were present in various organelles. Collinearity analysis between the tea plant and Arabidopsis thaliana genomes revealed that the CsABC genes were homologous to the AtABC genes. Large gene fragment duplication analysis identified ten gene pairs as tandem repeats, and interaction network analysis demonstrated that CsABCs interacted with various types of target genes, with protein interactions also occurring within the family. Tissue expression analysis indicated that CsABCs were highly expressed in roots, stems, and leaves and were easily induced by drought and cold stress. Moreover, qRT-PCR analysis of the relative expression level of the gene under drought and cold stress correlated with the sequencing results. Identifying ABC genes in tea plants lays a foundation for the classification and functional analysis of ABC family genes, which can facilitate molecular breeding and the development of new tea varieties.