Targeted disruption of a single sex pheromone receptor gene completely abolishes in vivo pheromone response in the silkmoth.

Hidefumi Mitsuno,Masashi Tabuchi,Hideki Sezutsu,Akihisa Mikami,Keiro Uchino,Takeshi Sakurai,Feng Zhang,Ryohei Kanzaki

doi:10.1038/srep11001

Abstract

Male moths use species-specific sex pheromones to identify and orientate toward conspecific females. Odorant receptors (ORs) for sex pheromone substances have been identified as sex pheromone receptors in various moth species. However, direct in vivo evidence linking the functional role of these ORs with behavioural responses is lacking. In the silkmoth, Bombyx mori, female moths emit two sex pheromone components, bombykol and bombykal, but only bombykol elicits sexual behaviour in male moths. A sex pheromone receptor BmOR1 is specifically tuned to bombykol and is expressed in specialized olfactory receptor neurons (ORNs) in the pheromone sensitive long sensilla trichodea of male silkmoth antennae. Here, we show that disruption of the BmOR1 gene, mediated by transcription activator-like effector nucleases (TALENs), completely removes ORN sensitivity to bombykol and corresponding pheromone-source searching behaviour in male moths. Furthermore, transgenic rescue of BmOR1 restored normal behavioural responses to bombykol. Our results demonstrate that BmOR1 is required for the physiological and behavioural response to bombykol, demonstrating that it is the receptor that mediates sex pheromone responses in male silkmoths. This study provides the first direct evidence that a member of the sex pheromone receptor family in moth species mediates conspecific sex pheromone information for sexual behaviour.

Highlights

Male moths use species-specific sex pheromones to identify and orientate toward conspecific females
These results demonstrate that BmOR1 is the receptor responsible for pheromone responses in the silkmoth; providing the first direct evidence that a member of moth sex pheromone receptor mediates pheromone responses for sexual behaviour in in vivo
To characterize the functional role of a sex pheromone receptor BmOR1 for the detection of bombykol and corresponding behavioural responses in in vivo, we generated BmOR1-knockout silkmoths using transcription activator-like effector nucleases (TALENs) that were designed to target the 2nd exon of the BmOR1 gene (Fig. 1a)

Summary

Introduction

Male moths use species-specific sex pheromones to identify and orientate toward conspecific females. These receptors have been characterized based on observations showing that ectopic expression confers heterologous cell responsiveness to pheromone component(s) in corresponding species, male antennae-specific or -biased expression patterns, histological localization in ORNs in pheromone sensitive olfactory sensilla, and amino acid sequence similarity among species These ORs are hypothesized to play a central role in the detection and discrimination of pheromones, and to mediate pheromone information for behavioural responses in male moths. The transgenic rescue of the BmOR1 gene in bombykol-sensitive ORNs restored the behavioural responses of BmOR1-knockout males These results demonstrate that BmOR1 is the receptor responsible for pheromone responses in the silkmoth; providing the first direct evidence that a member of moth sex pheromone receptor mediates pheromone responses for sexual behaviour in in vivo

Methods

Results

Conclusion