GhMYB94-activated GhLTP1 couples cuticle barrier formation with membrane lipid remodeling to confer water-deficit tolerance in cotton.

Water-deficit severely limits cotton (Gossypium hirsutum) yield, yet how plants coordinate cuticle barrier formation with membrane lipid remodeling under water-deficit remains unknown. Through WGCNA of water-deficit transcriptomes, we identified GhLTP1, a lipid transfer protein, as the hub gene of the water-deficit-responsive module. GhLTP1 encodes a secreted protein localized to the epidermal cell wall and apoplast. Silencing GhLTP1 impaired water-deficit tolerance and caused intracellular accumulation of cutin precursors (O-acyl-ω-hydroxy fatty acids) coupled with reduced epicuticular waxes, particularly C29 and C31n-alkanes, indicating that GhLTP1 is required for cuticular lipid accumulation. Notably, GhLTP1 silencing also triggered adaptive remodeling of cellular and thylakoid membrane lipids, by increasing unsaturation, very-long-chain fatty acid incorporation, and adjusting phospholipid-to-galactolipid ratios, consistent with cuticle defects exacerbating water loss while redirecting carbon flux from wax synthesis toward membrane lipids. We further show that GhMYB94 directly binds the GhLTP1 promoter to activate its expression, and GhMYB94-silenced plants phenocopy GhLTP1-RNAi lines. Our findings establish the GhMYB94-GhLTP1 module as a regulatory node that coordinates cuticle formation with membrane lipid remodeling to confer water-deficit tolerance in cotton.