Characterization of the Expression and Functions of Two Odorant-Binding Proteins of Sitophilus zeamais Motschulsky (Coleoptera: Curculionoidea)
1
Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, College of Plant Protection, Anhui Agricultural University, Hefei 230036, Anhui, China
2
Department of Entomology, University of Maryland, College Park, MD 20742, USA
*
Author to whom correspondence should be addressed.
†
Ying Zhang and Chen Shen contributed equally to this work.
Insects 2019, 10(11), 409; https://doi.org/10.3390/insects10110409
Received: 25 September 2019 / Revised: 13 November 2019 / Accepted: 14 November 2019 / Published: 15 November 2019
(This article belongs to the Special Issue Semiochemicals and Insect Behavior)
Odorant-binding proteins (OBPs) are important in insect chemical communication. The objective of this research was to identify the functions of two OBPs in Sitophilus zeamais. 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 S. zeamais responded strongly to 4-hydroxy-3-methoxybenzaldehyde and valeraldehyde from Sorghum bicolor. 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.
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Keywords:
Sitophilus zeamais; odorant-binding protein; expression pattern; host volatiles; ligand-binding spectrum; RNA interference; behavioral responses
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MDPI and ACS Style
Zhang, Y.; Shen, C.; Xia, D.; Wang, J.; Tang, Q. Characterization of the Expression and Functions of Two Odorant-Binding Proteins of Sitophilus zeamais Motschulsky (Coleoptera: Curculionoidea). Insects 2019, 10, 409.
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