An Evolutionarily Conserved Function of Grainyhead in Orchestrating Insect Wing Development

The development of insect appendages is governed by deeply conserved genetic programs, even as developmental strategies diverge widely across taxa. In this study, we identify the conserved transcription factor Grainyhead (Grh) as a crucial regulator of insect wing development. In the silkworm Bombyx mori, CRISPR/Cas9-mediated knockout of BmGrh did not compromise larval viability but resulted in severe wing defects in adults, including crumpled and non-expandable wings. Similarly, tissue-specific knockdown of DmGrh in Drosophila melanogaster wing imaginal discs led to pupal lethality, a sex-biased eclosion rate, and adults exhibiting crumpled wings with disrupted wing hair polarity. Comparative transcriptomics revealed that loss of DmGrh function predominantly downregulates genes associated with cuticle structure and extracellular matrix organization in both species. In Drosophila, chromatin immunoprecipitation further confirmed that DmGrh directly binds to regulatory regions of these downregulated cuticle-related genes. Through functional screening, we identified the cuticle protein gene cpr65Ea as a key downstream effector, whose knockdown recapitulated the wing morphogenesis and eclosion defects observed in DmGrh RNA interference individuals. Moreover, extending our investigation to an agricultural pest, RNAi-mediated silencing of SfGrh in the white-backed planthopper (Sogatella furcifera) impaired wing expansion and completely abolished flight ability. Our findings establish Grh as an evolutionarily conserved regulator of insect wing development and highlight its potential as a novel genetic target for pest management by disrupting flight capacity and dispersal.