|Li, Hui - Huazhong Agricultural University|
|Pan, Xiang- Yu - Huazhong Agricultural University|
|Chen, Li-zhen - Huazhong Agricultural University|
|Wang, Dian-xuan - Henan Agricultural University|
|Wang, Man-qun - Huazhong Agricultural University|
Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2014
Publication Date: 5/15/2015
Citation: Li, H., Pan, X., Chen, L., Wang, D., Zhang, A., Wang, M. 2015. Expression profile and ligand-binding characterization of odorant-binding protein 2 in Batocera horsfieldi (Hope). Journal of Applied Entomology. 139(5):361-369.
Interpretive Summary: The longhorned beetle (LB) is one of the most abundant and destructive insect pests of forest trees and is widely distributed throughout world. The larvae bore into the inner bark and sapwood of tree trunks, making them susceptible to wind damage. Adult LB has evolved a sensitive olfactory system to locate host plants and mates from a distance. In collaborative research, a new protein involved in detection of chemical signals, called odorant binding protein (OBP), from one species of LB widely distributed in China has been identified and levels of OBP in a variety of tissues from the male insect body have been quantitatively measured. Although a sex attractant for this species has not been identified, the chemicals engaged in odorant reception have been warranted. Our findings provide insight into the functions of OBP in perception of volatile odorants; and provide the foundation for researchers and regulatory agencies to develop the novel strategies to manage this pest.
Technical Abstract: Odorant-binding proteins (OBPs) are important components in insect olfactory systems that transport semiochemicals through the aqueous sensillum lymph to surface of olfactory receptor neurons. In this study, we cloned the cDNA of odorant-binding protein 2 (BhorOBP2) in Batocera horsfieldi (Hope) and measured the level of the BhorOBP2 mRNA in a variety of tissues using quantitative reverse transcription and real-time polymerase chain reaction (qRT-PCR). We found that the BhorOBP2 mRNA was primarily expressed in antennae; the level was higher in males than in females and correlated with age and mating status. The BhorOBP2 mRNA was also expressed in the labial palps at relatively high level, suggesting that it might have a role in gustation as well. In order to find out what kind of function of the BhorOBP2 protein will engage in odorant reception, recombinant BhorOBP2 was expressed in Escherichia coli. Binding specificity of the protein for 18 developmentally relevant volatiles and host-plant-related metabolites were assessed using N-phenyl-1-naphthylamine as a fluorescent probe. Competitive fluorescence binding assays showed that BhorOBP2 bound a broad range of host-plant-related odorants, including (E)-2-hexenal, 2-methyl-butanal, salicylaldehyde, (1S)-(-)-verbenone, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, ß-pinene, and ethyl acetate. Our results imply that BhorOBP2 might play an important role in the selectivity and specificity of odorant reception.