Seed priming upregulates antioxidant defense and glyoxalase systems to conferring simulated drought tolerance in wheat seedlings

Abstract

This experiment was conducted to understand the protective effect of different priming agents [50 µM salicylic acid (SA), 4 mM ascorbic acid (AsA), and 2.5 mM NaCl] under simulated drought [15% (m/v) polyethylene glycol (PEG-6000)] in wheat. Drought caused higher proline accumulation, lower relative water content, chlorosis, and growth inhibition. Enhanced levels of the malondialdehyde and hydrogen peroxide were evident with higher reactive oxygen species (ROS) generation that disrupted the plant antioxidant defense system. The activities of antioxidant enzymes were also significantly declined under PEG-induced drought stress. Drought also increased methylglyoxal (MG) formation, which aggravated oxidative damage to the next folds. However, priming wheat seeds with SA, AsA and NaCl decreased ROS production by decreasing AsA, increasing glutathione content, and upregulating the antioxidant defense system. Additionally, increased activities of glyoxalase system enzymes (glyoxalase I and glyoxalase II) controlled the overproduction of MG in drought-stressed wheat seedlings. Indeed, seed priming helps to alleviate drought-induced oxidative damage by modulating the antioxidant defense system. However, AsA provided a better defense to plants against drought stress. Therefore, it can be concluded that priming wheat seeds with SA, AsA, and NaCl confers drought stress tolerance by upregulating antioxidant defense and glyoxalase systems, thus ensuring better seedling establishment.