Exogenous Myo-Inositol Enhances Drought Tolerance in Potato by Modulating Jasmonic Acid Signaling and Flavonoid Antioxidant Pathways

Drought is the major abiotic stress restricting potato seedling growth and tuber yield formation. Exogenous myo-inositol (MI) has been reported to alleviate stress effects in various crops. However, the optimal foliar MI concentration for potato and its underlying transcriptional responses to drought remain poorly understood. Using potato cultivar ‘Atlantic’ at the 4-week seedling stage, we subjected plants to 14-day drought stress and tested seven foliar MI concentrations (0.5, 1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 mM). The optimal 6.0 mM dose was determined via statistical comparisons integrating multiple phenotypic and physiological indices. Combined with transcriptome sequencing, weighted gene co-expression network analysis (WGCNA), and qPCR validation, we explored transcriptional responses linked to MI-mediated drought tolerance. Physiological assays showed 6.0 mM MI exerted the strongest drought-mitigating effects, alleviating drought-triggered growth suppression, photosystem disruption and oxidative injury. Transcriptome analysis identified abundant drought-responsive differentially expressed genes (DEGs) enriched in photosynthesis, jasmonic-acid signal transduction and flavonoid antioxidant metabolism. WGCNA uncovered three co-expression modules correlated with drought-tolerance traits, yielding hub transcripts StAOS, StFMO1 and StOMT1. qPCR verified sequencing-derived expression trends, though it cannot confirm gene function. Our results suggest 6.0 mM exogenous MI is associated with transcriptional reprogramming of photosynthetic protection, jasmonic-acid signaling and flavonoid antioxidant pathways, improving seedling drought tolerance. This study defines the optimal MI concentration for potato drought mitigation and identifies candidate drought-responsive genes, laying a foundation for further functional characterization and stress-tolerance breeding research.