Salicylic acid induces vanadium stress tolerance in rice by regulating the AsA-GSH cycle and glyoxalase system

Salicylic acid (SA) is a signaling molecule and behaves as an antioxidant that induces stress tolerance in plants against abiotic stress. The present study explored the rice seedling response to V stress and the role of SA in improving the V stress tolerance of rice seedlings. The rice seedlings were sown in Petri dishes and incubated in a climate-controlled chamber for 4 days without light for germination. After that, the rice seedlings were shifted into hydroponic solution and allowed to grow for 18 days in hydroponic solution. The roots of 21-day-old rice seedlings were pretreated with SA (200 μM) for 3 days, and exposed to V (35 mg L−1) stress for 7 days. After 7 days of V stress, rice seedlings were harvested to determine the root attributes, photosynthetic assimilation, reactive oxygen species (ROS), ascorbate-glutathione (AsA-GSH) pathway enzymes, antioxidant and glyoxalase enzyme activities, and plant growth parameters. The findings disclosed that pretreatment of rice seedlings with SA had a high SPAD index, chlorophyll pigment content, and photosynthetic assimilation resulted in better growth compared to non-SA-pretreated rice seedlings. Strikingly, SA sustains the V homeostasis by inhibiting the accumulation of V from rice root to shoot. Besides this, pretreatment of SA increased the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST), and ascorbate-glutathione (AsA-GSH) pathway enzymes, and also enhanced the ascorbate (AsA) and glutathione (GSH) level, and minimized the hydrogen peroxide (H2O2) and superoxide anion (O2-∙) of rice seedlings, by regulating the gene expression of antioxidant enzymes (OsCuZnSOD1, OsCaTB, OsGPX1, OsAPX1, OsGR2, and OsGSTU37). Furthermore, SA reduced methylglyoxal toxicity and enhanced glyoxalase enzyme activity by upregulating the genes expression of glyoxalase genes (OsGLYI-1 and OsGLYII-2) under V stress condition. Considering these findings demonstrated that SA may be utilized to reduce V availability to rice seedlings while also improving rice seedling growth and V stress resistance. Graphical abstract: [Figure not available: see fulltext.]