Exogenous Glutathione and Nitric Oxide Improve Waterlogging Stress Tolerance in Maize

Maize (Zea mays L.) is one of the major grain crops worldwide that is particularly vulnerable to waterlogging (WL) stress. Glutathione (GSH) and nitric oxide (NO) are known to protect plants from a variety of abiotic stresses; however, their potential for improving WL tolerance in maize remains unexplored. The present study examined the impact of exogenously applied GSH and NO on maize plants exposed to WL-stress. Our findings revealed that GSH + NO-treated waterlogged maize plants grew better and produced more biomass than only WL-stressed plants. The improved performance of GSH + NO-sprayed WL-stressed maize seedlings was supported by the increased root dry and fresh weight, shoot length, shoot dry and fresh weight, chlorophyll a, chlorophyll b, and carotenoid content. Exogenous GSH and NO treatments significantly enhanced the amounts of leaf proline, leaf soluble sugars, and total protein in maize seedlings, suggesting adaptive metabolic reprogramming under stress. The increased malondialdehyde (MDA) levels and accumulation of hydrogen peroxide (H₂O₂) in maize leaves and roots revealed that WL caused significant oxidative damage. Exogenous GSH, NO individually, and combinedly significantly decreased total H₂O₂ and MDA contents in both leaves and roots. Exogenous GSH and NO reduced oxidative stress by increasing peroxidase activity, ascorbic acid, and anthocyanin content in maize leaf and root tissues. Our findings emphasize the possible relevance of GSH and NO, simultaneously and individually, in enhancing adaptive mechanisms in maize seedlings for reducing WL-induced damage. Although the GSH + NO-mediated approach shows promise for mitigating WL-stress in maize under controlled conditions, further field-based investigations are required to validate its practical applicability.