Identification of genes expressed in the sex pheromone gland of the black cutworm Agrotis ipsilon with putative roles in sex pheromone biosynthesis and transport

Abstract

BackgroundOne of the challenges in insect chemical ecology is to understand how insect pheromones are synthesised, detected and degraded. Genome wide survey by comparative sequencing and gene specific expression profiling provide rich resources for this challenge. A. ipsilon is a destructive pest of many crops and further characterization of the genes involved in pheromone biosynthesis and transport could offer potential targets for disruption of their chemical communication and for crop protection.ResultsHere we report 454 next-generation sequencing of the A. ipsilon pheromone gland transcriptome, identification and expression profiling of genes putatively involved in pheromone production, transport and degradation. A total of 23473 unigenes were obtained from the transcriptome analysis, 86% of which were A. ipsilon specific. 42 transcripts encoded enzymes putatively involved in pheromone biosynthesis, of which 15 were specifically, or mainly, expressed in the pheromone glands at 5 to 120-fold higher levels than in the body. Two transcripts encoding for a fatty acid synthase and a desaturase were highly abundant in the transcriptome and expressed more than 40-fold higher in the glands than in the body. The transcripts encoding for 2 acetyl-CoA carboxylases, 1 fatty acid synthase, 2 desaturases, 3 acyl-CoA reductases, 2 alcohol oxidases, 2 aldehyde reductases and 3 acetyltransferases were expressed at a significantly higher level in the pheromone glands than in the body. 17 esterase transcripts were not gland-specific and 7 of these were expressed highly in the antennae. Seven transcripts encoding odorant binding proteins (OBPs) and 8 encoding chemosensory proteins (CSPs) were identified. Two CSP transcripts (AipsCSP2, AipsCSP8) were highly abundant in the pheromone gland transcriptome and this was confirmed by qRT-PCR. One OBP (AipsOBP6) were pheromone gland-enriched and three OBPs (AipsOBP1, AipsOBP2 and AipsOBP4) were antennal-enriched. Based on these studies we proposed possible A. ipsilon biosynthesis pathways for major and minor sex pheromone components.ConclusionsOur study identified genes potentially involved in sex pheromone biosynthesis and transport in A. ipsilon. The identified genes are likely to play essential roles in sex pheromone production, transport and degradation and could serve as targets to interfere with pheromone release. The identification of highly expressed CSPs and OBPs in the pheromone gland suggests that they may play a role in the binding, transport and release of sex pheromones during sex pheromone production in A. ipsilon and other Lepidoptera insects.

Metabolic engineering of Escherichia coli for production of biodiesel from fatty alcohols and acetyl-CoA

“…Rodriguez et al reported that 95 % tetradecyl alcohol can be converted to tetradecyl acetate by ATF1 in strain AL1050 with a title 137 mg/L after 48 h. However, GC/MS analysis of extracts from the strain of our study revealed that a large number of fatty alcohols failed to be effectively converted to FAAEs, suggesting that further optimization of ATF1 expression level or identifying a better alcohol acetyltransferase to replace ATF1 in the future is a promising strategy for enhancing FAAE production in genetically engineered microorganisms. Given the accumulated knowledge about alcohol acetyltransferase (Gu et al 2013), it is believed that high productivity of FAAE production can be achieved through this novel pathway by further strain engineering.…”

Insect pheromones: An overview of function, form, and discovery

“…mapped to phylogeny [253][254][255]. Detailed transcriptomic data of 1086 pheromone glands are available for several species [256][257][258][259]. …”

“…For instance, a collection 246 of five synergistic components secreted from the queen mandible 247 (collectively named the queen mandibular pheromone, QMP; 254 are also altered by queen pheromone activity. The chemical com- 255 plexity of the queen pheromone provides functional redundancy 256 and lowers the possibility of workers becoming desensitized to 257 individual components. 258 …”

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].…”