MicroRNAs of the mesothorax in Qinlingacris elaeodes, an alpine grasshopper showing a wing polymorphism with unilateral wing form

spalt is functionally conserved in Locusta and Drosophila to promote wing growth

Locusta has strong fly wings to ensure its long distance migration, but the molecular mechanism that regulates the Locusta wing development is poorly understood. To address the developmental mechanism of the Locusta flying wing, we cloned the Dpp target gene spalt (sal) and analyzed its function in wing growth in the Locusta. The Locusta wing size is apparently reduced with vein defects when sal is interfered by injection of dsRNA, indicating that sal is required for locust wing growth and vein formation. This function is conserved during the Drosophila wing development. To better understand sal’s function in wing growth, we then used Drosophila wing disc as a model for further study. We found that sal promotes cell proliferation in the whole wing disc via positive regulation of a microRNA bantam. Our results firstly unravel sal’s function in the Locusta wing growth and confirm a highly conserved function of sal in Locusta and Drosophila.