Salt tolerance in plants: Cascading damage, signaling networks, and coordinated adaptation

Soil salinization poses a major threat to global agriculture, severely constraining plant growth and crop productivity. In response to salt stress, plants have evolved a multi-layered defense network spanning from stress perception to physiological adaptation. This review synthesizes current knowledge on the molecular and physiological mechanisms underlying plant salt stress responses. We first dissect the diverse detrimental effects of salt stress, including osmotic stress, ionic toxicity, high pH stress, metabolic disturbance, and reactive oxygen species (ROS) burst, and there may be interactions among some factors. Their interactions can generate coupled or cascading effects, though the nature and extent of these relationships remain to be fully elucidated. Next, we focus on stress sensing mechanisms, particularly how ion and osmotic sensors at the plasma membrane convert extracellular signals into intracellular Ca 2+ signals, which serve as an early response hub. Building on this, we analyze the crosstalk among the salt overly sensitive (SOS) pathway, the abscisic acid (ABA)-centered hormonal signaling network, and ROS signaling, revealing how they act concertedly rather than independently to regulate downstream adaptive responses. Finally, we summarize plant adaptive strategies from five perspectives—ion homeostasis, osmotic adjustment, ROS scavenging, cytoskeletal dynamics, and cell wall remodeling—and propose how these strategies coordinate across spatial and temporal scales. By integrating these advances, this review aims to provide a comprehensive theoretical framework for understanding the molecular basis of plant salt tolerance, mining key genetic resources, and developing salt-tolerant crops.