Silencing of odorant binding protein gene AlinOBP4 by RNAi induces declining electrophysiological responses of Adelphocoris lineolatus to six semiochemicals

Abstract

Odorant binding proteins (OBPs) are believed to be important for transporting semiochemicals through the aqueous sensillar lymph to the olfactory receptor cells within the insect antennal sensilla. Here, we injected AlinOBP4-siRNA into the conjunctivum between prothorax and mesothorax of the lucerne plant bug, Adelphocoris lineolatus and evaluated the silencing of AlinOBP4 by reverse transcription polymerase chain reaction (RT-PCR) analysis, quantitative real-time PCR (qPCR) test and electroantennogram (EAG) assay. The combination of RT-PCR and qPCR analyses revealed that the levels of messenger RNA transcript were significantly reduced ∼95% in AlinOBP4-siRNA-treated A. lineolatus males and ∼75% in RNAi-treated females within 48 hours. It was found that there are different EAG responses between male and female bugs when the AlinOBP4 gene was silenced by RNAi. The EAGs of A. lineolatus to two plant volatiles, tridecanal and hexyl alcohol, were reduced 9.09% and 79.45% in RNAi-treated males, 62.08% and 62.08% in RNAi-treated females compared to the controls, separately. Antennae of RNAi-treated bugs showed significantly lower electrophysiological responses to four sex pheromone analogs, butyl butanoate, 1-hexyl butyrate, (E)-2-hexenyl butyrate and hexyl hexanoate. The EAG recordings were reduced 35.43%, 35.24%, 39.96% and 78.47% in RNAi-treated males and 64.52%, 18.13%, 36.88% and 49.52% in RNAi-treated females, respectively. The results suggested that AlinOBP4 might play dual-roles in the identification of plant volatiles and sex pheromones. It was suspected that AlinOBP4 may have different functions in odor perception between male and female A. lineolatus.

Identification, Expression Patterns, and Functional Characterization of Chemosensory Proteins in Dendroctonus armandi (Coleoptera: Curculionidae: Scolytinae)

“…This list corresponded well with the list of volatiles found to be bound by DarmCSP2 in fluorescence binding assays. Our results corroborate recent RNAi studies that demonstrated how the silencing of genes encoding OBPs or CSPs abolished or modified electrophysiological responses, influenced odor preferences, disrupted behavior, and altered morphology in insects (Maleszka et al, 2007 ; Gong et al, 2012 ; Yi et al, 2013 ; Wu et al, 2016 ; Dong et al, 2017 ; Zhang et al, 2017 ). Together, our results and previous work suggest that DarmCSP2 collaborates with multiple binding proteins (including other CSPs and OBPs) to transport numerous compounds.…”

Silencing the Odorant Binding Protein RferOBP1768 Reduces the Strong Preference of Palm Weevil for the Major Aggregation Pheromone Compound Ferrugineol

“…RNAi and electrophysiological approaches are widely used and well-accepted methods for the characterization of OBPs, especially PBPs, in insects (Xu et al, 2005 ; Laughlin et al, 2008 ; Biessmann et al, 2010 ; Pelletier et al, 2010 ). In addition, the use of RNAi and electrophysiological approaches in characterizing OBPs is well documented in mosquitoes (Biessmann et al, 2010 ; Pelletier et al, 2010 ), Drosophila (Xu et al, 2005 ; Laughlin et al, 2008 ); Aphis gossypii (Rebijith et al, 2016 ); Adelphocoris lineolatus (Zhang et al, 2017 ); and Helicoverpa armigera (Dong et al, 2017 ). Such attempts have confirmed the role of OBPs in olfaction, as carriers of hydrophobic odorants and pheromones through the aqueous environment of the sensillum lymph to ORs (Leal, 2013 ).…”

The role of chemosensory protein 10 in the detection of behaviorally active compounds in brown planthopper, Nilaparvata lugens

“…Insects can detect and discriminate semiochemicals through numerous receptors and olfactory proteins, including chemosensory proteins (CSPs), odorant binding proteins (OBPs), odorant receptors (ORs), sensory neuron membrane proteins (SNMPs), and odorant degrading enzymes (ODEs) (Pelosi et al ., ; Zhang Q. H. et al ., ). CSPs and OBPs are produced in non‐neuronal support cells and secreted in the lymphs of chemosensilla at high concentration (Pelosi et al ., ), while sensory organs such as antennae contain a defined olfactory system, which perceives and triggers a behavioral response to chemical signals (Zhang X. Y. et al ., ). Both CSPs and OBPs are small, soluble proteins of around 12–18 kDa having the capability to bind, deliver and recognize small external odorants (De Biasio et al ., ).…”