FOXO links wing form polyphenism and wound healing in the brown planthopper, Nilaparvata lugens. (March 2016) - Lin, Xinda
Abstract: Polyphenisms such as wing dimorphisms and caste determination are important in allowing animals to adapt to changing environments. The brown planthopper Nilaparvata lugens, one of the most serious insect agricultural pests, includes two wing forms, the long wing form (macropterous) and the short wing form (brachypterous). Long wings are specialized for migration, while short wings are found in individuals specialized for reproduction. While studying wing form polyphenism in the brown planthopper, we excised single wing pads from 4th instar nymphs in order to preserve transcriptional records to correlate with adult wing form. Surprisingly, we found that excision of one wing pad from a pair of the forewings changed the wing morph of the other wing after development to the adult, resulting in the short wing morph. Further experiments showed that not only excision or slicing of the wing pad, but also needle punctures in the abdomen all caused a significant increase in the proportion of nymphs developing into short winged adults. Thus wounding appears to cause a shift to short wing development. We then tested the transcriptional expression in N. lugens of the transcription factor FOXO, which has been shown to help mediate both wing polyphenism in brown planthoppers and wound healing in mice, after excision of the wing pad. Both NlFOXO and its downstream target Nl4EBP increased significantly after wing pad excision. These results indicate that FOXO mediates both wing development and wound healing in N. lugens, which results in an interesting linkage of these two physiological processes. Graphical abstract: Highlights: Wounding nymphs of Nilaparvata lugens causes a shift favoring development of the short winged morph. Wounding is accompanied by an increase in expression of the NlFOXO, in both damaged (wounded) and undamaged wing pads. RNAi knockdown of NlFOXO results in a shift to development of long winged adults in both control and wounded nymphs. NlFOXO appears to have a role in both wing form polyphenism and wound healing.