Nitric Oxide and Hydrogen Peroxide Coordinate to Improve Photosynthesis, Oxidative Defense, Osmoregulation, and Ions Homeostasis in Pea (Pisum sativum L.) Under Drought

Nitric oxide (NO) and hydrogen peroxide (H2O2) are essential signaling molecules in plants under stressful conditions because they are generated and distributed in several biological processes in spatiotemporal coordination. The available information on the effects of NO and H2O2 on photosynthesis, redox homeostasis, and osmotic adjustment, particularly in the context of nutrient acquisition under drought conditions, is limited. Four pea cultivars (Meteor, Sarsabz, Climax, and Supreme) were subjected to drought stress (100% and 60% field capacity). Plants were primed with individual and combined solutions of 0.1 mM NO and 1 mM H2O2. Plants were harvested ten days after drought imposition to measure physiological and biochemical modifications in plants under drought.Drought profoundly ebbed growth, chlorophyll content, photosynthesis, stomatal conductance, transpiration rate, and nutrient accumulation in all pea cultivars, while higher depression in these attributes was evident in cv. Meteor, cv. Climax, and cv. Supreme. Drought initiated oxidative injury reflected as higher electrolyte leakage, H2O2, and malondialdehyde content in pea cultivars. The endogenous NO content profoundly increased in pea cultivars in response to drought. Individual and combined NO and H2O2 subsided oxidative damage via an intensified antioxidant defense system. Likewise, NO and H2O2 performed osmotic adjustment through improved osmolyte accumulation. The uptake of essential nutrients was remarkably better in plants due to exogenous H2O2 and NO. The exogenous individual and combined NO and H2O2 reinforced osmolyte accumulation, nutrient uptake, and oxidative defense that might have bettered growth and yield in pea cultivars.