Comparative genome-wide identification and analysis of the COMT gene family in potato (Solanum tuberosum L.) and Arabidopsis ( Arabidopsis thaliana (L.) Heynh.)

Caffeic acid O-methyltransferase (COMT) is a key S-adenosyl-L-methionine (SAM)-dependent enzyme in the phenylpropanoid pathway, playing a crucial role in plant stress resistance, growth, and development through its functions in melatonin and lignin biosynthesis. While COMT genes have been extensively studied in other Solanaceae crops and functional studies of individual genes have been reported in potato (Solanum tuberosum L.), a genome-wide systematic analysis of this gene family in potato remains lacking. This study comprehensively identified 18 StCOMT genes in the potato genome, and these 18 StCOMT genes can be divided into two clusters. Bioinformatics analysis revealed that StCOMT proteins possess conserved structural features, including the O-methyltransferase domain and dimerization domain, with their promoter regions enriched in stress- and hormone-responsive cis-acting elements. Phylogenetic and collinearity analyses indicated high homology with tomato genes and suggested evolutionary expansion of this family through gene duplication. Expression profiling demonstrated distinct tissue-specific patterns and differential induction under various biotic and abiotic stresses, implying functional diversification among its members. Functional enrichment analysis further supported their involvement in key pathways such as phenylpropanoid and tryptophan metabolism. However, these conclusions are based on bioinformatic analyses and require further experimental validation. In summary, this study provides the first systematic genomic characterization of the StCOMT gene family in potato, offering valuable candidate gene targets for molecular breeding aimed at enhancing stress tolerance and agronomic traits in potato.