Transcriptomics-proteomics analysis reveals StCOMT1 regulates drought, alkali and combined stresses in potato

Transcriptome proteome association analysis screened candidate DEGs, DEPs, and DEGs/DEPs associated with potato response to drought, alkali, and combined stresses. Overexpression of StCOMT1 enhances potato drought and alkali tolerance. Drought and salinity have severely impeded potato (Solanum tuberosum L.) growth and development, significantly reducing global potato production. However, the molecular mechanisms regulating the combined drought and alkali stress process are not fully understood. This study compared the mRNA and protein expression profiles of potato under drought (PEG-6000), alkali (NaHCO₃), and combined (PEG-6000 + NaHCO₃) stresses by transcriptome and TMT proteomics sequencing to investigate the common or specific responses of 'Atlantic' potato to single and combined stresses of drought and alkali were preliminarily explored. It was found that 2215 differentially expressed genes (DEGs) and 450 differentially expressed proteins (DEPs) were jointly identified under drought, alkali, and combined stresses. Under drought, alkali, and combined stresses, 234, 185, and 246 DEGs/DEPs were identified, respectively. These DEGs, DEPs, and DEGs/DEPs identified revealed the potential roles of several signaling and metabolic pathways in mediating drought and alkali stress tolerance, including plant hormone signaling, MAPK signaling pathway, phenylpropanoid biosynthesis, and glutathione metabolism. Caffeic acid-O-methyltransferase (COMT) is an essential methylating enzyme in the phenylpropane biosynthetic pathway, which is involved in lignin synthesis and plays an important role in protecting plants from abiotic stresses. In this study, we investigated the changes in physiologic characteristics, such as growth, antioxidant defense, osmotic regulation and lignin accumulation, in overexpressing StCOMT1 (PT0001512/M0ZIL7) transgenic potato after stress. It proved that the gene has the function of adapting to drought and alkali stress, and provided a theoretical basis for further research on the resistance mechanism of the gene in drought and alkali tolerance in potato.