Expression in antennae and reproductive organs suggests a dual role of an odorant-binding protein in two sibling Helicoverpa species.

Ya-Lan Sun,Paolo Pelosi,Chen-Zhu Wang,Ling-Qiao Huang

doi:10.1371/journal.pone.0030040

Ya-Lan Sun, Paolo Pelosi + Show 2 more

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https://doi.org/10.1371/journal.pone.0030040

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Abstract

Odorant-binding proteins (OBPs) mediate both perception and release of semiochemicals in insects. These proteins are the ideal targets for understanding the olfactory code of insects as well as for interfering with their communication system in order to control pest species. The two sibling Lepidopteran species Helicoverpa armigera and H. assulta are two major agricultural pests. As part of our aim to characterize the OBP repertoire of these two species, here we focus our attention on a member of this family, OBP10, particularly interesting for its expression pattern. The protein is specifically expressed in the antennae of both sexes, being absent from other sensory organs. However, it is highly abundant in seminal fluid, is transferred to females during mating and is eventually found on the surface of fertilised eggs. Among the several different volatile compounds present in reproductive organs, OBP10 binds 1-dodecene, a compound reported as an insect repellent. These results have been verified in both H. armigera and H. assulta with no apparent differences between the two species. The recombinant OBP10 binds, besides 1-dodecene, some linear alcohols and several aromatic compounds. The structural similarity of OBP10 with OBP1 of the mosquito Culex quinquefasciatus, a protein reported to bind an oviposition pheromone, and its affinity with 1-dodecene suggest that OBP10 could be a carrier for oviposition deterrents, favouring spreading of the eggs in these species where cannibalism is active among larvae.

Highlights

Two sibling Lepidopteran species Helicoverpa armigera and H. assulta are major agricultural pests
Sequencing of Odorant-binding proteins (OBPs) in H. armigera and H. assulta Using specific primers designed on the nucleotide sequences of orthologous proteins in H. virescens, we obtained several amplification products encoding OBPs in both H. armigera and H. assulta
A comparison of our sequences with those published showed that 7 of the 10 OBPs we identified in H. armigera had been reported [18], some amino acid substitutions were observed, indicating the existence of multiple forms for these proteins

Summary

Introduction

Two sibling Lepidopteran species Helicoverpa armigera and H. assulta are major agricultural pests. We report the identification of three additional OBPs in H. armigera and eight in H. assulta and the characterization of one of them, that we name OBP10, in both species, interesting for its dual expression pattern in antennae and male reproductive organs. A comparison of our sequences with those published showed that 7 of the 10 OBPs we identified in H. armigera had been reported [18], some amino acid substitutions were observed, indicating the existence of multiple forms for these proteins.

Results

Conclusion