Research Advances on Salt Tolerance and Molecular Mechanism of Maize

Soil salinization causes multiple hazards to maize production by inhibiting seed germination, affecting root growth, hindering water and nutrient absorption, weakening photosynthesis, and reducing yield and quality. Currently, soil salinization is a major abiotic stress that significantly reduces maize yield and quality in China. Therefore, understanding the molecular mechanisms underlying maize's salt tolerance and developing salt-tolerant maize varieties are crucial for boosting maize production and ensuring food security. This article reviews recent research advances on the effects of salt stress on maize growth and development, the physiological regulatory mechanisms of salt tolerance in maize, the regulatory mechanisms of salt-tolerant genes in maize, and the screening and breeding of salt-tolerant maize varieties. The effects of salt stress on maize vegetative growth stage primarily manifest as early inhibition of root and seedling growth. During reproductive growth stages, salt stress mainly impacts photosynthesis and material transport, leading to reduced above-ground biomass, decreased grain yield, and declined quality. The physiological mechanisms underlying salt tolerance in maize mainly rely on osmotic regulation and ion homeostasis. Ion homeostasis is primarily reflected in the selective absorption and distribution of Na+ and K+, ion transport systems in cell membranes, vacuolar ion sequestration, regulation of K+/Na+ ratio, and signaling pathways controlling ion balance. So far, researches have showed salt-tolerance genes in maize primarily enhance salt tolerance by regulating Na+/K+ balance and mitigating reactive oxygen species (ROS) accumulation. Finally, the current status of screening and breeding salt-tolerant maize hybrids is analyzed, and the research perspectives of salt tolerance of maize are discussed, aiming to provide valuable insights for the development of salt-tolerant maize germplasm and the breeding of salt-tolerant hybrids.