Transcription factor Nlci is essential for wing dimorphism in the brown planthopper, Nilaparvata lugens

The brown planthopper (BPH) alternatively develops into either macropterous or brachypterous morphs in response to environmental stimuli, enhancing its fitness and dispersal. Despite several key upstream regulator genes involved in wing morphs switching having been identified, the downstream pathways governing wing plasticity remain unclear. Here, we harvested the 4th instar nymphal wing buds from macropterous strain (MS) and brachypterous strain (BS) for transcriptome sequencing. Individually, 3 025 and 3 273 differentially expressed genes (DEGs) were identified in forewing and hindwing buds, respectively, between 2 strains. Functional enrichment analysis revealed that these DEGs were significantly enriched in various categories related to signal transduction and metabolism. Among these, the Hedgehog (Hh) pathway was implicated in environmental information processing and wing development regulating. Knocking down the transcription factor Cubitus interruptus (Nlci) of the Hh pathway significantly reduced the wing size and resulted in malformed wings of both strain adults. Additionally, the expression levels of downstream genes (Nlptc, Nlen, and Nldpp) were inhibited to varying degrees. Furthermore, the expression levels of Nlci and its downstream genes were decreased when injected with double-stranded (ds)NlInR1, but increased in dsNlInR2 treatment. Silencing of Nlci partially antagonized the acceleration effect of dsNlInR2 treatment on wing development, leading to an intermediate wing morph. Our findings expand the regulatory role of the Hh pathway in the wing dimorphism of BPH, providing new insights into the mechanisms underlying wing development.