TRANSCRIPTOME ANALYSIS OF AN ENDOPARASITOID WASP Cotesia chilonis (HYMENOPTERA: BRACONIDAE) REVEALS GENES INVOLVED IN SUCCESSFUL PARASITISM

Abstract

For successful parasitization, parasitiods usually depend on the chemosensory cues for the selection of hosts, as well as a variety of virulence factors introduced into their hosts to overcome host immunity and prevent rejection of progeny development. In bracovirus-carrying wasps, the symbiotic polydnaviruses act in manipulating development and immunity of hosts. The endoparasitoid Cotesia chilonis carrying bracovirus as a key host immunosuppressive factor is a superior endoparasitoid of rice stem borer, Chilo suppressalis. So far, genomic information for C. chilonis is not available and transcriptomic data may provide valuable resources for global studying on physiological processes of C. chilonis, including chemosensation and parasitism at molecular level. Here, we performed RNA-seq to characterize the transcriptome of C. chilonis adults. We obtained 27,717,892 reads, assembled into 38,318 unigenes with a mean size of 690 bp. Approximately, 62.1% of the unigenes were annotated using NCBI databases. A large number of chemoreception-related genes encoding proteins including odorant receptors, gustatory receptors, odorant-binding proteins, chemosensory proteins, transient receptor potential ion channels, and sensory neuron membrane proteins were identified in silico. Totally, 72 transcripts possessing high identities with the bracovirus-related genes were identified. We investigated the mRNA expression levels of several transcripts at different developmental stages (including egg, larva, pupae, and adult) by quantitative real-time PCR analysis. The results revealed that some genes had adult-specific expression, indicating their potential significance for mating and parasitism. Overall, these results provide comprehensive insights into transcriptomic data of a polydnavirus-carrying parasitoid of a rice pest.

Characterization of joining sites of a viral histone H4 on host insect chromosomes

“…plutellae parasitism because teratocytes and other 156 CpBV genes might play crucial roles in altering host gene expression. Similar viral histone H4s have been found in other Cotesia -associated BVs [35]. Thus, viral histone H4 might be a main parasitic factor in Cotesia -associated parasitism.…”

Suppressive activity of a viral histone H4 against two host chromatin remodelling factors: lysine demethylase and SWI/SNF

“…The truncated form of CpBV-H4 after deleting the extended N-terminal tail will lose its inhibitory functions, suggesting that CpBV-H4 can epigenetically control host gene expression (Hepat & Kim, 2011). Similar viral histone H4s have been found in other Cotesia-associated BVs (Qi et al, 2015). It has been reported that CpBV-H4 can interact with eukaryotic histone proteins to form nucleosomal octamer in an in vitro reconstruction assay (Hepat et al, 2013).…”

Antennal transcriptome and odorant binding protein expression profiles of an invasive mealybug and its parasitoid

“…A previous similar study showed that only one CSP gene was identified in the antenna of paper wasp Polistes dominulus (Calvello et al., ). Only two CSP unigenes have been identified in the transcriptome of C. chilonis adults thus far (Qi et al., ).…”

“…A total of 170 OR genes were found in the genome of honeybee A. mellifera (Robertson & Wanner, ). In the genomic analysis of N. vitripennis , a total of 301 OR genes were discovered, among which 76 are pseudogenes and 225 are apparently intact ORs (Robertson, Gadau, & Wanner, ); 117 OR‐related unigenes were identified in the transcriptome of Cotesia chilonis adult (Qi et al., ). In this study, 226 candidate ORs were identified in the antennal transcriptome of A. bambawalei .…”