Stress-Specific Carbonylation and Proteasome 20S Activity in Potato Under Drought, Elevated Temperature, and Combined Stresses: Linking Oxidative Damage to Proteome Regulation.

Drought and elevated temperature are major abiotic stresses that limit potato growth and productivity; however, their combined effects on biomass and oxidative damage to proteins remain poorly understood. We investigated individual and interactive effects of drought and elevated temperature on growth traits, yield, protein carbonylation, 20S proteasome activity, and the leaf proteome. Results show that while an elevated temperature alone did not significantly impair vegetative biomass or yield, it markedly intensified the negative impacts of drought during simultaneous exposure. Drought and combined stress substantially reduced stem and leaf mass, as well as assimilation area. Biochemically, drought induced protein carbonylation and stimulated 20S proteasome activity. Interestingly, elevated temperature reduced carbonylation and proteasome activity, yet its presence in combined stress exacerbated oxidative damage compared to drought. Proteomic analysis revealed stress-specific carbonylation of molecular chaperones, antioxidant enzymes, and proteins involved in photosynthesis, glycolysis, and energy metabolism. These results suggest that while potato plants exhibit resilience to moderately elevated temperature, the synergistic effect of heat and drought triggers a more severe oxidative challenge. This requires enhanced proteolytic and antioxidant mechanisms to maintain growth and productivity under complex stress conditions.