From Model Plants to Staple Crops: Molecular Mechanisms of Plant Saline–Alkali Tolerance

Soil salinization, as a key constraint to global agricultural sustainable development, has threatened over one billion hectares of farmland, posing severe challenges to staple crop production. Therefore, this review summarizes important advances in the molecular mechanisms of salt–alkali tolerance from the model plant Arabidopsis thaliana to staple crops (rice, maize, and wheat) and compares the commonalities and differences in physiological structure and molecular regulatory networks among these species. Studies have shown that plants respond to saline–alkali stress mainly through conserved mechanisms, including salt overly sensitive (SOS) signaling pathway-mediated ion homeostasis, accumulation of osmoprotectants, reactive oxygen species (ROS) scavenging, and coordination of multiple hormone signals. However, different species have evolved unique adaptive strategies: Arabidopsis has revealed core regulatory pathways, but its simple root system limits direct application in crops; rice employs root barriers and a stem node “ion filter” to precisely regulate Na+ transport; maize utilizes the C4 photosynthetic pathway along with efficient osmotic adjustment and tissue compartmentalization to enhance tolerance; and wheat achieves ion detoxification through TaHKT allele variation and vacuolar sequestration. Looking forward, future breeding for salt–alkali tolerance should adopt a “crop-centric” approach, focusing on the mining and molecular design of superior alleles, combined with gene editing and multi-trait integration, to provide a theoretical basis and strategic support for developing high-yield and stable crop varieties adapted to saline–alkali lands.