A Transcriptome Survey Spanning Life Stages and Sexes of the Harlequin Bug, Murgantia histrionica

Abstract

The harlequin bug, Murgantia histrionica (Hahn), is an agricultural pest in the continental United States, particularly in southern states. Reliable gene sequence data are especially useful to the development of species-specific, environmentally friendly molecular biopesticides and effective biolures for this insect. Here, mRNAs were sampled from whole insects at the 2nd and 4th nymphal instars, as well as sexed adults, and sequenced using Illumina RNA-Seq technology. A global assembly of these data identified 72,540 putative unique transcripts bearing high levels of similarity to transcripts identified in other taxa, with over 99% of conserved single-copy orthologs among insects being detected. Gene ontology and protein family analyses were conducted to explore the functional potential of the harlequin bug’s gene repertoire, and phylogenetic analyses were conducted on gene families germane to xenobiotic detoxification, including glutathione S-transferases, carboxylesterases and cytochrome P450s. Genic content in harlequin bug was compared with that of the closely related invasive pest, the brown marmorated stink bug, Halyomorpha halys (Stål). Quantitative analyses of harlequin bug gene expression levels, experimentally validated using quantitative real-time PCR, identified genes differentially expressed between life stages and/or sexes.

De novo formation of an aggregation pheromone precursor by an isoprenyl diphosphate synthase-related terpene synthase in the harlequin bug

“…We compared transcript abundance of MhTPS and MhFPPS between different sexes, developmental stages, and tissues by RT-PCR and qRT-PCR analyses. In agreement with mRNA levels determined by transcriptome analysis ( 43 ), MhTPS transcript levels were significantly higher (∼37-fold) in mature males than in mature and immature females ( Fig. 2 A and SI Appendix , Fig.…”

“…While no genes with sequence similarity to plant or microbial TPSs could be identified, two trans -IDS–like sequences ( MhIDS-1 and MhIDS-2 ) annotated as FPP synthase (FPPS)-like genes were retrieved. According to the transcriptome results by Sparks et al ( 43 ), MhIDS-1 (GECQ01420512.1; MG662378.1) mRNA levels are low in mature females but show a ∼13-fold higher accumulation in mature males, while MhIDS-2 (GECQ01414919.1; MG662379.1) transcript levels are equal in both sexes. cDNAs of both genes were amplified from RNA extracted from mature male bugs.…”

“…1 ). To identify genes involved in the formation of the murgantiol pheromone precursor, we queried a transcriptome dataset from different sexes and developmental stages of M. histrionica ( 43 ) with plant and microbial TPS sequences and trans -IDS–type sequences of I. pini FPPS (AAX55631.1) and GPPS/TPS (AAX55632.1), Bombyx mori (silk moth) FPPS1 (NP_001036889.1) and FPPS2 (NP_001093301.1), and Drosophila melanogaster (fruit fly) FPPS (NP_477380). While no genes with sequence similarity to plant or microbial TPSs could be identified, two trans -IDS–like sequences ( MhIDS-1 and MhIDS-2 ) annotated as FPP synthase (FPPS)-like genes were retrieved.…”

Functional characterization of CYP4G11—a highly conserved enzyme in the western honey bee Apis mellifera

“…The duplication of the ancestor of the CYP4G subfamily likely occurred very early in the evolutionary history of insects, as indicated by the fact that species in the orders Hymenoptera, Lepidoptera, Diptera and Coleoptera all have two extant CYP4G genes, each on either CYP4G11‐Clade1 or CYP4G11‐Clade2. Hemiptera species, by contrast, appear to have undergone a proliferation of CYP4G, with as many as five paralogs in some genomes (Sparks et al, ); for phylogenetic analyses, 115 CYP4G sequences were used. The best matches to CYP4G genes were also searched in the genome of the damselfly Calopteryx splendens (Ioannidis et al, ), in the hope of finding more ancestral CYP4Gs.…”

Brown marmorated stink bug, Halyomorpha halys (Stål), genome: putative underpinnings of polyphagy, insecticide resistance potential and biology of a top worldwide pest

“…7 demonstrate that they are quite different from β-esterases and are potentially misplaced in our phylogenetic tree, likely due to a long branch-attraction artifact. Sparks et al (2017) [145] combined these data with protein sequences from the harlequin bug, Murgantia histronica, and the resulting phylogeny (see Figure S3 of Sparks et al (2017) [145]) places the neurodevelopment-associated carboxylesterases within their own monophyletic clade, an outgroup to the β-esterase clade. The additional information utilized by this multi-species analysis suggests it may convey a more accurate representation of the overall relationships among COEs in H. halys than does the single-species phylogeny, underscoring the importance of sequencing genomes from additional pentatomid taxa to enable comparative genomics studies (and thus, more informative phylogenetic gene family analyses) in the future.…”