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

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.