Bioprospecting a Natural Antioxidant Peptide for Tomato Biostimulation Under Water Limitations: Physiological Approach

Abstract Drought causes major agricultural losses, threatening food security worldwide. Thus, innovative strategies have been explored to improve crop tolerance to drought. This work focused on one natural peptide (PpT-2) with antioxidant activity, unexplored in plant applications, to evaluate its effectiveness in mitigating drought effect on Solanum lycopersicum L. plants. For that, tomato plants were foliar sprayed with different doses of PpT-2 (0, 15 or 150 mg L −1 ) and exposed to water Stressed and UnStressed conditions. The plant growth, photosynthesis and oxidative stress-related parameters were evaluated. Plant treatment with PpT-2, mostly at the highest concentration, alleviated diverse effects induced by water restriction: stimulated CO 2 assimilation; improved Φ PSII , Fv/Fm and Fv’/Fm’; amended net CO 2 assimilation rate and water use efficiency; restricted H 2 O 2 accumulation and lipid peroxidation; stimulated SOD activity. Under UnStressed conditions, PpT-2 induced some degree of stomatal closure, nevertheless without restricting CO 2 availability for the non-photochemical processes of photosynthesis, besides of decreasing H 2 O 2 content and CAT activity. Overall, PpT-2 application controlled H 2 O 2 accumulation, and under water limitations improved both photochemical and non-photochemical processes of photosynthesis and promoted drought tolerance, underscoring its potential for managing drought stress in crop species.