Genome-Wide Characterization of Solanum tuberosum CCoAOMT Gene Family and Identification of StCCoAOMT Genes Involved in Anthocyanin Biosynthesis.

Background: The caffeoyl-CoA-O methyltransferase (CCoAOMT) family plays essential roles in the methylation of various secondary metabolites, including anthocyanins. Despite the wide identification of the CCoAOMT family in plants, the characterization and function of CCoAOMT protein members in Solanum tuberosum remain poorly understood.

Methods and results: In this study, a total of 12 StCCoAOMT members were identified in the genome of S. tuberosum using the Blastp and HMM search and were unevenly located on eight chromosomes. Collinearity analysis revealed that four tandem duplicated gene pairs and two segmental duplicated gene pairs existed in the S. tuberosum genome, demonstrating that duplication events play a key role in the expansion of the CCoAOMT family. All StCCoAOMTs were clustered into group I and group II based on phylogenetic analysis, which was further verified by the conserved motifs and gene structures analysis. The cis-acting elements analysis illustrated that StCCoAOMTs might be important for photosynthesis, hormone responses, and abiotic stress. Expression analysis demonstrated that StCCoAOMT genes have diverse transcript levels in various tissues and that StCCoAOMT10 was significantly expressed in purple potatoes with abundant anthocyanin content according to RNA-seq data and qRT-PCR assays. In addition, the subcellular localization assay validated that the StCCoAOMT10 protein was mainly localized in the cytoplasm and nucleus.

Conclusions: These results will be of great importance for a better understanding of the features of CCoAOMT family members, especially of the candidate genes involved in the methylation of anthocyanins in S. tuberosum, and also for improving the nutritional quality of S. tuberosum.