The GhWL1‐GhH1‐GhGA2OX1 Transcriptional Module Regulates Cotton Leaf Morphology

Abstract Leaf morphology critically influences photosynthetic efficiency, directly affecting crop yield and quality. In this study, a T‐DNA insertion mutant ( wl‐D ), characterized by a wrinkled‐leaf phenotype, is identified. Genetic analysis reveals that this phenotype is governed by a single dominant gene, WRINKLED‐LEAF 1 (GhWL1) , which is highly expressed in wl‐D compared to the wild type (WT). Overexpression of GhWL1 in WT caused curling at leaf edges, while suppression of GhWL1 in wl‐D restored normal leaf morphology, validating its functional role. Further analysis demonstrated that GhWL1 interacts with GhH1 , a protein with a KNOX1 structural domain, to regulate leaf development. Overexpression of GhH1 in WT results in a leaf shrinkage phenotype similar to wl‐D , whereas suppressing GhH1 in wl‐D restored normal leaf morphology, indicating that GhH1 acts downstream of GhWL1 . The GhWL1‐GhH1 complex directly binds to the promoter of GhGA2OX1 (gibberellin 2‐beta‐dioxygenase 1), positively regulating its expression. Overexpression of GhGA2OX1 in WT mimicked the leaf shrinkage phenotype observed in plants overexpressing GhH1 . These findings establish the GhWL1‐GhH1 ‐GhGA2OX1 module as a critical pathway in regulating leaf development, offering valuable insights into the genetic and hormonal networks controlling leaf morphological diversity.