Characterization of the Distal-less gene homologue, NlDll, in the brown planthopper, Nilaparvata lugens (Stål).

The brown planthopper, Nilaparvata lugens (Stål), is a globally devastating insect pest of rice, particularly in eastern Asia. Distal-less or Dll is a highly conserved and well studied transcription factor required for limb formation in invertebrates and vertebrates. We have identified a homologue of this gene, NlDll, and demonstrated that it is expressed in all life stages of N. lugens, particularly in adult brachypterous females. When we compared between specific adult tissues it was expressed most strongly in wings. Using RNAi techniques we demonstrated that downregulation of NlDll in the 3rd instar larvae led to the disrupted development of the leg, while downregulation of NlDll in the 5th instar larvae led to abnormal wing formation. Ectopic over-expression of NlDll in Drosophila melanogaster using the GAL4-UAS system led to fatal or visible phenotypic changes such as the loss of normal wing structure and disrupted haltere structure. Our work suggests that NlDll is a conserved homologue of Distal-less and is required for both leg development and wing structure. Since researches have shown that Dll is required for wing morphogenesis, understanding the role of NlDll during the wing development will further provide a basis for revealing the molecular mechanism of the wing dimorphism in brown planthopper. In the future, NlDll could be used as a target gene for brown planthopper pest management in the field.