Two Minus-C odorant-binding proteins (OBPs) involved in the perception of kairomone (+)-3-carene in Dendroctonus valens.
The olfactory system is pivotal for insects to detect external chemical signals and regulate essential life processes. Dendroctonus valens, an invasive forest pest, displays strong chemotaxis toward the plant kairomone (+)-3-carene. To unravel the molecular mechanism underlying olfactory recognition, we identified 28 odorant-binding proteins (OBPs) from D. valens via transcriptome sequencing and identified DvalOBP6 and DvalOBP18 as potential key candidates for this host kairomone component using qRT-PCR. Tissue expression analysis revealed that these two Minus-C OBPs are predominantly expressed in olfactory-related tissues (antennae, legs, and wings) with distinct sexual dimorphism. Homology modeling and molecular docking showed that both proteins adopt a typical six-α-helix fold, and bind (+)-3-carene primarily via hydrophobic interactions with binding energies of -5.53 kcal/mol and -4.96 kcal/mol, respectively. RNA interference of DvalOBP6 or DvalOBP18 significantly abolished the olfactory preference of D. valens adults for (+)-3-carene. Collectively, our findings demonstrate that DvalOBP6 and DvalOBP18 play critical roles in (+)-3-carene perception, providing a theoretical basis for the development of green pest control technologies targeting insect olfactory communication.