Expression and Functional Analysis of Two Odorant-Binding Proteins from Bradysia odoriphaga (Diptera: Sciaridae).

Two OBP genes, BodoOBP1 and BodoOBP2, were cloned from Bradysia odoriphaga, a major agricultural pest of Chinese chives. The amino acid sequence alignment of both BodoOBPs showed high similarity. Fluorescence competitive binding assays revealed that both BodoOBPs have a moderate binding affinity to dipropyl trisulfide. Tissue expression profiles indicated that both BodoOBPs are antennae-specific and more abundant in the male antennae than in the female antennae. Developmental expression profile analysis indicated that expression levels of both BodoOBPs were higher in the male adult stage than in the other developmental stages. Both BodoOBPs also showed differential expression in pre- and postmating adults. RNAi assays indicated that ability of dsOBPs-treated males to detect females was significantly reduced compared to controls. Attraction of plant volatile dipropyl trisulfide to dsOBPs-treated adults was also significantly lower than in the control. Our findings indicate that both BodoOBPs are involved in host-seeking behavior and in detecting sex pheromones.