Identification and Characterization of Pheromone Receptors and Interplay between Receptors and Pheromone Binding Proteins in the Diamondback Moth, Plutella xyllostella

Abstract

Moths depend on olfactory cues such as sex pheromones to find and recognize mating partners. Pheromone receptors (PRs) and Pheromone binding proteins (PBPs) are thought to be associated with olfactory signal transduction of pheromonal compounds in peripheral olfactory reception. Here six candidate pheromone receptor genes in the diamondback moth, Plutella xyllostella were identified and cloned. All of the six candidate PR genes display male-biased expression, which is a typical characteristic of pheromone receptors. In the Xenopus-based functional study and in situ hybridization, PxylOR4 is defined as another pheromone receptor in addition to the previously characterized PxylOR1. In the study of interaction between PRs and PBPs, PxylPBPs could increase the sensitivity of the complex expressing oocyte cells to the ligand pheromone component while decreasing the sensitivity to pheromone analogs. We deduce that activating pheromone receptors in olfactory receptor neurons requires some role of PBPs to pheromone/PBP complex. If the chemical signal is not the pheromone component, but instead, a pheromone analog with a similar structure, the complex would have a decreased ability to activate downstream pheromone receptors.

Evolution of two receptors detecting the same pheromone compound in crop pest moths of the genus Spodoptera

“…In a similar way, only two minor components of the S. littoralis pheromone blend, (Z)9-14:OAc and (Z,E)-9,12-14:OAc, could be assigned to a receptor, leaving all the other minor components orphans. This suggests that more PRs await further identification and/or that PBPs could modify Spodoptera PR response spectra as observed in P. xylostella (Sun et al, 2013).…”

An olfactory receptor from Apolygus lucorum (Meyer-Dur) mainly tuned to volatiles from flowering host plants

“…To investigate the specificity of the four selected ORs, we expressed them together with AlucOrco in Xenopus oocytes, following a strategy successfully adopted with the ORs from other insect species Sun et al, 2013;Wang et al, 2010;Zhang et al, 2013aZhang et al, , 2014. The ORs thus expressed were stimulated with an odorant collection of 71 chemicals, including green leaf volatiles (GLVs) and other terpenoids, both aliphatic and aromatic, at the concentration of 10 À4 M.…”

Pheromone Reception in Moths

“…46 Since then, much progress has been made in identifying new PRs in moths, with characterizations of receptors in more than 15 species. [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] Recently, studies on PRs have mainly involved functional characterization of PRs from different moth species by heterologous expression in HEK293 cells, 49,51 Xenopus oocytes, 46 or Drosophila antennal transgenic expression systems. 62 The first PRs in insects were identified in B. mori, BmorOR1 and BmorOR3.…”

“…51 Our study on interplay between PRs and PBPs from Plutella xylostella showed that PxylPBPs could increase the sensitivity of the PR-expressing oocytes to the ligand pheromone component while decreasing the sensitivity to pheromone analogs. 59 However, Xu et al found that when bombykol and bombykal are solubilized with BmorPBP1, there was no enhancement in selectivity; by contrast, both ligands were trapped by BmorPBP1 leading to dramatically reduced responses. 107 How the PBPs function in pheromone sensing, whether the PBPs release the pheromones to activate the ORNs alone or instead as a complex, is still uncertain.…”