GhNAC47 activates GhSKS6‐mediated cell wall remodeling to promote cotton chemical defoliation

Chemical defoliation is essential for mechanized harvesting of cotton (Gossypium hirsutum L.), yet the molecular mechanisms governing abscission zone (AZ) cell fate and cell-wall remodeling remain unresolved. Here, single-nucleus RNA sequencing (snRNA-seq) coupled with Monocle2 trajectory analysis delineates a pseudotemporal transition of protective-layer cells from C16_0 to C16_1, which coincides with AZ maturation. We identify the cell-wall glycoprotein GhSKS6 as a central hub in this differentiation process. CRISPR/Cas9-mediated knockout of GhSKS6 impairs AZ fracture-layer formation, delays leaf abscission, and downregulates genes associated with hemicellulose and xyloglucan remodeling. Subcellular localization and plasmolysis assays confirm the residency of GhSKS6 in the cell wall, while its overexpression in protoplasts accelerates cell wall regeneration. Moreover, the NAC transcription factor GhNAC47 directly binds to the GhSKS6 promoter to activate its expression, thereby modulating cotton leaf abscission. Our findings reveal a regulatory module involving GhNAC47 and GhSKS6 that coordinates protective-layer formation and cell-wall remodeling, offering precise molecular targets for breeding machine-harvested cotton cultivars.