Characterization of the Expression and Functions of Two Odorant-Binding Proteins of Sitophilus zeamais Motschulsky (Coleoptera: Curculionoidea)

• Published in: Insects (Basel, Switzerland) Switzerland), 2019-11, Vol.10 (11), p.409
• Main Authors: Zhang, Ying, Shen, Chen, Xia, Daosong, Wang, Jian, Tang, Qingfeng
• Format: Article
• Language: English
• Subjects: Affinity; Agricultural commodities; behavioral responses; Binding; binding capacity; Chemical communication; Cloning; Double-stranded RNA; Eclosion; Enzymes; expression pattern; Fluorescence; Food; Genes; host volatiles; Insects; Laboratories; ligand-binding spectrum; Molecular biology; odor compounds; odorant receptors; odorant-binding protein; Odorants; olfactometers; protein content; Proteins; quantitative polymerase chain reaction; reverse transcriptase polymerase chain reaction; RNA interference; RNA-mediated interference; Signal transduction; Sitophilus zeamais; Software; Sorghum; Sorghum bicolor; Transcription; vanillin; Variance analysis; Volatile compounds; Volatiles; Western blotting
• ISSN: 2075-4450; 2075-4450
• DOI: 10.3390/insects10110409

Odorant-binding proteins (OBPs) are important in insect chemical communication. The objective of this research was to identify the functions of two OBPs in . qRT-PCR and western blot (WB) were performed to investigate the expression profiles at the transcript and protein levels, respectively. Fluorescence competitive binding assays were used to measure the ability of the OBPs to bind to host volatiles, and a Y-tube olfactometer was used to verify the results (attraction/no response) via behavioral experiments. The RNAi was used to verify the function by knocking down the ability of proteins to bind odorants. qRT-PCR showed the highest expression SzeaOBP1 and SzeaOBP28 at the low-instar larva (LL) and eclosion adult (EA) stages, respectively. WB showed that both SzeaOBP1 and SzeaOBP28 were highly expressed in the EA stage. Fluorescence competitive binding assays indicated that SzeaOBP1 exhibited extremely high binding affinity with cetanol. SzeaOBP28 exhibited a pronounced binding affinity for 4-hydroxy-3-methoxybenzaldehyde. The behavioral experiment showed that the adult responded strongly to 4-hydroxy-3-methoxybenzaldehyde and valeraldehyde from . The RNAi knockdown individuals displayed behavioral differences between normal insects and dsRNA (SzeaOBP1)-treated insects. We infer that they both have functions in perception and recognition of host volatiles, whereas SzeaOBP28 may also have other functions.