Metabolic Landscape and Core Regulatory Network of Monocotyledonous and Dicotyledonous Plants in Drought Response...

Drought stress severely restricts plant growth and substantially reduces crop productivity. Although drought-response mechanisms have been extensively characterized within individual plant species, the conserved metabolic strategies shared across species remain insufficiently understood. To elucidate both conserved and species-specific metabolic mechanisms underlying drought adaptation, we performed an integrated transcriptomic and metabolomic analysis in rice, maize, and tomato. Profiling of 543 annotated metabolites revealed strikingly divergent baseline metabolic landscapes: tomato leaves were enriched in triglycerides and anthocyanins, whereas maize and rice accumulated higher levels of glycerophospholipids, tricin-derived flavonoids, and B vitamins. Under drought conditions, these differences were further reflected in the distinct sets of differentially accumulated metabolites (DAMs) detected in tomato (121), rice (98), and maize (94). Despite these species-specific signatures, we identified a conserved drought-responsive module consisting of five phenolamides that were consistently induced across all three species. Reconstruction of the associated regulatory network uncovered divergent enzymatic control strategies governing phenolamide biosynthesis: the drought-induced BAHD acyltransferases OsPHT4 in rice and SlPHT3 in tomato exhibited broad-spectrum catalytic activities, whereas the maize homolog ZmPHT4 fulfilled a similar biosynthetic role through constitutive, non-drought-inducible activity. Together, this study provides a comprehensive metabolic framework for plant drought response and demonstrates that extensive species-specific metabolic architectures and transcriptional regulatory divergence coexist beneath a conserved core metabolomic response, offering promising targets for the precise genetic enhancement of crop drought tolerance.