Can the Application of Exogenous Nitric Oxide (S-Nitrosoglutathione—GSNO) Confer Tolerance to Water Deficit in Maize Plants?

Nitric oxide is a key signaling molecule that instigates several changes in plant metabolism by inducing tolerance to environmental stress. In this context, the objective of this study was to evaluate the application of exogenous nitric oxide (S-nitrosoglutathione—GSNO), on the biochemical and physiological characteristics of maize plants exposed to water deficit. The experiment was carried out in a greenhouse using a completely randomized design, with six treatments and five replications. Analyses were performed on plants at phenological stage V6 (six fully expanded leaves) of the sensitive hybrid BRS 1030 under irrigation, with water deficit and water deficit with the application of two S-nitrosoglutathione concentrations (50 and 100 µM). For comparative purposes, the tolerant maize hybrid DKB 390 was also subjected to these conditions, without the application of S-nitrosoglutathione. Biometrics, spad, gas exchange, sugars, glutathione and antioxidant enzymes were evaluated. Water deficit causes stomatal and biochemical limitations in maize plants. However, the application of 50 µM S-nitrosoglutathione restores the gas exchange of BRS 1030, probably inhibiting photosynthetic limitations. The same concentration increases the sugar levels in these plants (roots and shoots), contributing to the osmotic adjustment of maize under stress. It was also observed that the production of oxidized glutathione may have consumed the hydrogen peroxide resulting from stress, which may have decreased the activity of peroxidases, maintaining redox balance. A concentration of 50 µM S-nitrosoglutathione improves the physiology and biochemistry of maize plants, inducing tolerance of the sensitive hybrid (BRS 1030) to water deficit.