Recent Insights into the Molecular Mechanisms of Salt Tolerance in Melon (Cucumis melo L.)

Salt stress represents one of the most critical abiotic constraints limiting global agricultural productivity by adversely affecting plant growth, metabolism, and yield. Soil salinization disrupts water uptake and nutrient homeostasis, leading to ionic toxicity, osmotic imbalance, and oxidative stress that collectively impair crop development. Cucumis melo, a major horticultural crop of significant economic value, exhibits high sensitivity to salinity. Recent advances have elucidated that melon adapts to salt stress through intricate physiological and molecular mechanisms involving osmotic adjustment, ion transport regulation, antioxidant defense, and transcriptional reprogramming. Several pivotal genes, such as CmNHX1, CmHKT1;1, CmCML13, CmAPX27, and CmRAV1, etc., have been identified to participate in multiple signaling pathways governing salt tolerance in melon. In this review, we comprehensively summarize the physiological effects of salt stress on melon growth, elucidating the key molecular mechanisms underlying salt tolerance, particularly those associated with ion homeostasis, antioxidant defense, and transcriptional regulation. The review further discusses current strategies and future perspectives for the genetic improvement of salt tolerance. Collectively, this review provides a theoretical framework and valuable reference for future research on the molecular basis of salt tolerance and breeding of salt-tolerant melon cultivars.