Identification of StCCoAOMT gene family and analysis of resistance of StCCoAOMT1 and StCCoAOMT7 genes to drought, alkaline salt and combined stresses in potato

Drought and alkaline salt stress act synergistically on potato, affecting growth and causing reduced yield and quality. Lignin plays a key role in potato resistance to abiotic stresses, and most of the key enzymes in its synthetic pathway were involved in plant stress response. Among them, caffeoyl CoA O-methyltransferase (CCoAOMT) is a key enzyme for G-type lignin synthesis, and the StCCoAOMT gene is involved in potato lignin synthesis and response to plant stress in response to adversity. The study identified 13 StCCoAOMT genes, which were classified into four subgroups by evolutionary analysis. We have analyzed their physicochemical properties, gene structures, motifs, and cis-acting elements. StCCoAOMT family genes are subject to purification selection, and tandem repeats are the primary driver of gene duplication. The collinearity relationships with other species analysis showed that the StCCoAOMT genes are evolutionarily distinct from monocotyledonous plants. Through transcriptomic analysis and RT-qPCR validation of the tissue-specific expression patterns of StCCoAOMT genes under drought, alkaline salt, and combined stress conditions, we identified the stress-responsive gene StCCoAOMT7.We also obtained the homologous gene, StCCoAOMT1, which has the highest degree of similarity to the Arabidopsis thaliana gene At4g34050, which is responsive to drought and salt stresses, by sequence comparison. VIGS analysis revealed that NbCCoAOMT1 and NbCCoAOMT7 silenced tobacco plants displayed reduced resistance compared to WT plants under drought, alkaline salt, and combined stress. It is speculated that the StCCoAOMT1 and StCCoAOMT7 genes positively regulate drought, alkaline salt, and combined stress. The subcellular localization of StCCoAOMT1 and StCCoAOMT7 proteins was investigated in tobacco. The results indicate that both proteins may function in the nucleus, plasma membrane, and cytoplasm, providing new insights into the molecular mechanisms underlying plant defense and stress responses. StCCoAOMT1 and StCCoAOMT7 were screened as drought, alkaline salt, and combined stress response genes.