Magnesium Hydride Confers Osmotic Tolerance in Mung Bean Seedlings by Promoting Ascorbate–Glutathione Cycle

Abstract

Despite substantial evidence suggesting that hydrogen gas (H2) can enhance osmotic tolerance in plants, the conventional supply method of hydrogen-rich water (HRW) poses challenges for large-scale agricultural applications. Recently, magnesium hydride (MgH2), a hydrogen storage material in industry, has been reported to yield beneficial effects in plants. This study aimed to investigate the effects and underlying mechanisms of MgH2 in plants under osmotic stress. Mung bean seedlings were cultured under control conditions or with 20% polyethylene glycol (PEG)-6000, with or without MgH2 addition (0.01 g L−1). Under our experimental conditions, the MgH2 solution maintained a higher H2 content and longer retention time than HRW. Importantly, PEG-stimulated endogenous H2 production was further triggered by MgH2 application. Further results revealed that MgH2 significantly alleviated the inhibition of seedling growth and reduced oxidative damage induced by osmotic stress. Pharmacological evidence suggests the MgH2-reestablished redox homeostasis was associated with activated antioxidant systems, particularly the ascorbate–glutathione cycle. The above observations were further supported by the enhanced activities and gene transcriptional levels of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase. Overall, this study demonstrates the importance of MgH2 in mitigating osmotic stress in mung bean seedlings, providing novel insights into the potential agricultural applications of hydrogen storage materials.

Keywords

• osmotic stress
• magnesium hydride
• hydrogen gas
• antioxidant systems
• ascorbate–glutathione cycle
• mung bean