Genes involved in sex pheromone biosynthesis of Ephestia cautella, an important food storage pest, are determined by transcriptome sequencing

Abstract

BackgroundInsects use pheromones, chemical signals that underlie all animal behaviors, for communication and for attracting mates. Synthetic pheromones are widely used in pest control strategies because they are environmentally safe. The production of insect pheromones in transgenic plants, which could be more economical and effective in producing isomerically pure compounds, has recently been successfully demonstrated. This research requires information regarding the pheromone biosynthetic pathways and the characterization of pheromone biosynthetic enzymes (PBEs). We used Illumina sequencing to characterize the pheromone gland (PG) transcriptome of the Pyralid moth, Ephestia cautella, a destructive storage pest, to reveal putative candidate genes involved in pheromone biosynthesis, release, transport and degradation.ResultsWe isolated the E. cautella pheromone compound as (Z,E)-9,12-tetradecadienyl acetate, and the major pheromone precursors 16:acyl, 14:acyl, E14-16:acyl, E12-14:acyl and Z9,E12-14:acyl. Based on the abundance of precursors, two possible pheromone biosynthetic pathways are proposed. Both pathways initiate from C16:acyl-CoA, with one involving ∆14 and ∆9 desaturation to generate Z9,E12-14:acyl, and the other involving the chain shortening of C16:acyl-CoA to C14:acyl-CoA, followed by ∆12 and ∆9 desaturation to generate Z9,E12-14:acyl-CoA. Then, a final reduction and acetylation generates Z9,E12-14:OAc. Illumina sequencing yielded 83,792 transcripts, and we obtained a PG transcriptome of ~49.5 Mb. A total of 191 PBE transcripts, which included pheromone biosynthesis activating neuropeptides, fatty acid transport proteins, acetyl-CoA carboxylases, fatty acid synthases, desaturases, β-oxidation enzymes, fatty acyl-CoA reductases (FARs) and fatty acetyltransferases (FATs), were selected from the dataset. A comparison of the E. cautella transcriptome data with three other Lepidoptera PG datasets revealed that 45 % of the sequences were shared. Phylogenetic trees were constructed for desaturases, FARs and FATs, and transcripts that clustered with the ∆14, ∆12 and ∆9 desaturases, PG-specific FARs and potential candidate FATs, respectively, were identified. Transcripts encoding putative pheromone degrading enzymes, and candidate pheromone carrier and receptor proteins expressed in the E. cautella PG, were also identified.ConclusionsOur study provides important background information on the enzymes involved in pheromone biosynthesis. This information will be useful for the in vitro production of E. cautella sex pheromones and may provide potential targets for disrupting the pheromone-based communication system of E. cautella to prevent infestations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1710-2) contains supplementary material, which is available to authorized users.

Key genes of the sex pheromone biosynthesis pathway in female moths are required for pheromone quality and possibly mediate olfactory plasticity in conspecific male moths in Spodoptera litura

“…When specific local environmental conditions persist, selection forces from the environment may result in directional or divergent selection. The genes involved in the sex pheromone biosynthesis of Heliothis virescens (Vogel et al, 2010) and Ephestia cautella (Antony et al, 2015) were recently determined by transcriptome sequencing. However, the genetic changes associated with the variations and divergence in sex pheromone signals remain largely unknown (Groot et al, , 2013Lassance et al, 2010Lassance et al, , 2013.…”

Comparative transcriptome analysis provides insights of anti‐insect molecular mechanism of Cassia obtusifolia trypsin inhibitor against Pieris rapae

“…As demonstrated previously, larval midgut played essential role in the resistance to allelochemicals from host plants, it was necessary to understand the molecular mechanism by which COTI alter the physiological balance in migdut of P. rapae . De novo assembly of transcriptome has been widely used to identify the growing and developmental genes, hormone biosynthetic genes, and signaling pathway genes in Lepidoptera insects (Antony et al., ; Liu et al., ; Pan et al., ; Park & Kim, ; Qi et al., ; Xu et al., ). Here, transcriptome sequencing was carried out to obtain systematic information related to response in P. rapae midgut.…”

Biotechnological potential of insect fatty acid-modifying enzymes

“…Although moth FARs usually exhibit a broad substrate preference [77,89,111,120,122,123], some of them display specificity to unsaturated substrates with a double bond in either the E or Z configuration [119], a particular chain length and double bond position [120], or a system of conjugated double bonds [118]. Given the multiple FAR paralogs generally present in insect genomes [13,14,16,17,111,124] and limited knowledge of their properties, there is a demand to perform functional characterization of these biologically and biotechnologically relevant enzymes. FARs from insects other than moths are virtually unexplored.…”

“…The diversification of the pheromone-biosynthetic enzymes likely has been driven by evolutionarily imposed requirements on sex pheromone signal specificity [11,12]. A broad spectrum of insect pheromone-biosynthetic enzymes has already been functionally characterized, and transcriptomic sequencing (RNA-seq) of pheromone glands using next-generation sequencing has identified new candidates for characterization [13][14][15][16][17][18][19]. RNA-seq of other insect glands and tissues may open the door to the discovery of many additional enzymes with remarkable biosynthetic capabilities [8].…”