An Orphan Pheromone Receptor Affects the Mating Behavior of Helicoverpa armigera.

Tianyu Huang,Song Cao,Guirong Wang,Yang Liu,Jie Shen

doi:10.3389/fphys.2020.00413

Abstract

The Lepidoptera is the second largest insect order, which has the most extensive knowledge of sex pheromones and mechanisms of pheromone communication since the identification of the first insect pheromone in Bombyx mori. In the past 15 years, pheromone receptors have been identified and functionally characterized in many moth species. HarmOR14 is a typical pheromone receptor of Helicoverpa armigera which showed no response to the tested pheromones in Xenopus oocyte expression system, but its orthologous gene in Heliothis virescens, HvirOR14 could be activated by pheromones in the same expression system. To assess the possible functions of OR14 in vivo, in this study, we knocked out this gene using CRISPR/Cas9 system and compared the mating behaviors and EAG response to pheromones between the wild type and mutant strains. Our results showed that OR14 mutants did not affect the mating rate or the EAG response to pheromones but could prolong the mating duration and change the mating time in undefined manners, which extends our understanding to this kind of pheromone receptors.

Highlights

Sex pheromone plays a pivotal role in intraspecific communication between individuals of opposite sex, which likely facilitate the successful survival and reproduction of many species
We found that OR13 was the receptor for the major pheromone component, Z11-16:Ald, OR6 and OR14b both responded to two minor pheromone compounds, Z9-14:Ald and Z9-16:Ald, and OR16 was narrowly tuned to Z914:Ald and a behavioral antagonist, Z11-16:OH, while the other three pheromone receptors (PRs), OR11, OR14 and OR15 all showed no response to all the pheromones or analogs (Liu Y. et al, 2013; Yang et al, 2017)
Considering OR14 is only expressed in male antenna, we speculated that OR14 only affected mating behaviors of males

Summary

Introduction

Sex pheromone plays a pivotal role in intraspecific communication between individuals of opposite sex, which likely facilitate the successful survival and reproduction of many species. The precise reception of pheromone signals is accomplished by male-specific olfactory receptor neurons (ORNs) located in the hair-like cuticular organs-sensilla that are non-randomly distributed on moth antennae (Kanaujia and Kaissling, 1985). Extensive progress has elucidated that several molecular elements are involved in the recognition of pheromone at the molecular level in moth including pheromone binding proteins (PBPs) (Zhu et al, 2016), sensory neuron membrane proteins (SNMPs) (Pregitzer et al, 2014), odorant degrading enzymes (ODEs) (Ishida and Leal, 2005; Durand et al, 2011), pheromone receptors (PRs) (Sakurai et al, 2015; Chang et al, 2017) and Pheromone Receptor of Helicoverpa armigera a highly conserved and broadly expressed (Larsson et al, 2004) odorant receptor coreceptor (Orco) (Nakagawa et al, 2005; Sato et al, 2008). PRs expressed on the dendrites of ORNs determine their selectivity and specificity, suggesting that PR genes are key elements for determining pheromone preference in male moths

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Conclusion