Engineering drought tolerance in sugarcane via EMS mutagenesis: Physio-transcriptomic dissection of a resilient mutant

Sugarcane is a globally significant industrial crop, and drought represents a key abiotic stress limiting its yield and quality. To develop drought-tolerant germplasm, this study chemically mutated callus tissue from sugarcane material YT93–159 using ethyl methanesulfonate (EMS). A drought-tolerant mutant, 1–17, was subsequently identified through PEG-6000-simulated drought stress screening. Compared with YT93–159, mutant 1–17 exhibited higher antioxidant enzyme activity and a lower degree of membrane lipid peroxidation. Transcriptome analysis revealed that EMS mutagenesis alone induced 6244 differentially expressed genes (DEGs) in the mutant, while drought stress further amplified this transcriptional difference, generating 12,754 DEGs between the mutant and YT93–159. GO and KEGG enrichment analyses indicate that the mutant's drought tolerance stems from a multi-level synergistic defense mechanism: Structurally, the physical barrier function was enhanced by upregulating genes associated with cell wall tissues (such as COBRA-like protein 5 and cellulose synthase CesAs ) and cuticle biosynthesis (such as GPAT3 ); Physiologically, it ensures energy supply by maintaining stable expression of key genes in the photosynthetic system; In terms of hormone regulation, the signaling pathways of hormones such as auxin, jasmonic acid, and brassinosteroids have been reprogrammed. This study elucidates the multiple molecular mechanisms by which EMS mutagenesis confers drought tolerance to sugarcane, providing valuable genetic resources and theoretical foundations for drought-resistant sugarcane breeding. Furthermore, this mutant and the key genes identified from it provide valuable resources for the molecular breeding of drought-tolerant sugarcane varieties.