Silicon-mediated regulation of antioxidant defense and glyoxalase systems confers drought stress tolerance in Brassica napus L.

Drought stress is considered as a major constraint for the production of crops around the world; therefore we need some mechanistic strategies to cope drought stress adverse effects. Silicon (Si) plays a vital role in major physiological, metabolic, and/or functional roles in plants facing abiotic stress conditions as an essential mineral nutrient. In the current study, we investigated Si-induced physiological role in plants exposed to moderate and short-term drought exposure (induced by polyethylene glycol, PEG). Exogenous application of Si (1 mM SiO₂) significantly induced tolerance under short term drought (10 and 20% PEG) exposure. Silicon protects photosynthetic pigments and decreased oxidative stress (decreased lipid peroxidation and H₂O₂ accumulation) due to the increase in ascorbate (AsA) and glutathione (GSH) pool; activity of antioxidant enzymes viz. catalase (CAT), ascorbate peroxidase (APX), glutathione S-transferase (GST), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR) and, enzymes of glyoxalase systems, leaf relative water content (RWC) and the content of proline in Brassica napus grown under both levels of drought (moderate; 10% and severe 20%), however, the effect was more promising under moderate stress. Here, we concluded that exogenous application of Si under short-term drought significantly improved antioxidants enzymes, AsA-GSH pool, glyoxalase systems and proline in drought-stressed plants was associated with the protective role and maintained the redox status of the plants.