Selenium in crop stress adaptation: physiological and biochemical mechanisms, molecular regulation, and prospects for crop improvement
Selenium (Se) is a beneficial trace element for the human body and also plays a crucial role in crop growth under stress conditions. This review systematically summarizes the regulatory effects, molecular mechanisms, and practical applications of Se in crop response to biotic and abiotic stresses. Specifically, Se alleviates stress damage through multiple pathways, including protecting the photosynthetic system, enhancing antioxidant defense capacity, regulating osmotic substance synthesis, maintaining intracellular ion balance, inducing defense-related substances, and promoting phenylpropanoid metabolism. At the molecular level, Se achieves stress regulation mainly by modulating the expression of stress-related genes (e.g., antioxidant, photosynthetic, and ion transport genes) and participating in key signal transduction pathways such as calcium signaling, mitogen-activated protein kinase (MAPK) cascade, and plant hormone signaling. In agricultural practice, different types of Se fertilizers (inorganic, organic, and nano-Se) are widely applied via soil or foliar application, and case studies on rice ( Oryza sativa L.) and wheat ( Triticum aestivum L. ) have confirmed their remarkable effects in improving crop stress resistance, yield, and quality. Despite significant progress, the core “Se-gene-stress” molecular regulatory network remains unclear, and precise Se-application technologies and long-term environmental impact monitoring still need optimization. Future research should focus on these deficiencies, integrate multi-omics and gene editing technologies to clarify the key regulatory mechanisms, optimize Se fertilizer application schemes, and explore Se’s synergistic effects with other elements, thereby providing strong theoretical support and practical guidance for sustainable agricultural development under stress conditions.