BarH1 regulates the expression of conserved odorant-binding protein 22 from Dastarcus helophoroides

Chemical signals are pivotal in establishing tritrophic interactions among host plants, herbivorous insects, and natural enemies. Previous studies have shown that evolutionarily conserved MaltOBPs in Monochamus alternatus and DhelOBPs in Dastarcus helophoroides contribute to the establishment of pine -pest - natural enemy tritrophic interactions by recognizing the same volatile emitted by the host during crucial developmental stages. We hypothesized that the transcriptional regulatory mechanisms of evolutionarily conserved OBPs respectively from pests and enemies are similar. In this study, we identified the promoter region of DhelOBP22 through chromosome walking and discovered that transcription factor BarH1, which have been proved to regulate the expression of MaltOBP19 in M. alternatus, regulates the expression of DhelOBP22 by binding to its promoter region, as evidenced by dual-luciferase assays and electrophoretic mobility shift assay (EMSA). When the BarH1 gene was silenced using RNAi, the expression of DhelOBP22 was inhibited, leading to the disappearance of the attracted behavior of mated female D. helophoroides adults towards camphene. This study underscores that conserved transcriptional regulation mechanisms play a role in regulating the expression of evolutionarily conserved OBPs respectively from herbivores and natural enemies.