Sugarcane under siege: integrated physiological, molecular responses and mitigation strategies to salinity and drought stress.

Saline soil and drought are among the most devastating abiotic stresses constraining sugarcane (Saccharum spp.) production globally, with soil salinity affecting over 1,125 Mha worldwide and drought causing severe yield losses in tropical and subtropical agroecosystems. As a glycophytic C4 crop supplying ~80% of the world's sugar, sugarcane is particularly vulnerable, with threshold salinity tolerance at a mere 1.7 dS m-1 electrical conductivity (EC). This review integrates recent developments in the physiological, biochemical, and molecular responses of sugarcane during stress conditions. Under salinity, photosynthetic CO2 efficiency, chlorophyll integrity, source-sink partitioning, reactive oxygen species (ROS) metabolism, phytohormone signaling, and osmolyte accumulation are altered based on the sugarcane cultivars and cultivation regions. Under drought, stomatal regulation, root hydraulics, abscisic acid (ABA) cascades, and the expression of dehydrin and late embryogenesis abundant (LEA) proteins govern tolerance. At the molecular level, ion-transporter genes (SOS pathway), DREB/ERF transcription factors, aquaporins, and small RNAs constitute central regulatory hubs. Mitigation strategies, including agronomic interventions, exogenous osmoprotectants, plant growth-promoting rhizobacteria, biochar amendment, and advanced breeding tools such as CRISPR/Cas9, marker-assisted selection, and transgenic approaches, are comprehensively discussed for sustainable sugarcane production.