Transcriptomic insight into the immune defenses in the ghost moth, Hepialus xiaojinensis, during an Ophiocordyceps sinensis fungal infection

Meng

Ning

et al. 2017

Sci. China Life Sci.

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Monochamus alternatus, the main vector beetles of invasive pinewood nematode, has established a symbiotic relationship with a native ectotrophic fungal symbiont, Sporothrix sp. 1, in China. The immune response of M. alternatus to S. sp. 1 in the coexistence of beetles and fungi is, however, unknown. Here, we report that immune responses of M. alternatus pupae to infection caused by ectotrophic symbiotic fungus S. sp. 1 and entomopathogenic fungus Beauveria bassiana differ significantly. The S. sp. 1 did not kill the beetles while B. bassiana killed all upon injection. The transcriptome results showed that the numbers of differentially expressed genes in M. alternatus infected with S. sp. 1 were 2-fold less than those infected with B. bassiana at 48 hours post infection. It was noticed that Toll and IMD pathways played a leading role in the beetle's immune system when infected by symbiotic fungus, but upon infection by entomopathogenic fungus, only the Toll pathway gets triggered actively. Furthermore, the beetles could tolerate the infection of symbiotic fungi by retracing their Toll and IMD pathways at 48 h. This study provided a comprehensive sequence resource of M. alternatus transcriptome for further study of the immune interactions between host and associated fungi.Monochamus alternatus, symbiotic fungus, Beauveria bassiana, RNA-seq, immune signaling pathway Citation:Zhang, W., Meng, J., Ning, J., Qin, P., Zhou, J., Zou, Z., Wang, Y., Jiang, H., Ahmad, F., Zhao, L., and Sun, J. (2017). Differential immune responses of Monochamus alternatus against symbiotic and entomopathogenic fungi. Sci China Life Sci 60, 902-910.

Section: Discussionmentioning

confidence: 61%

Differential immune responses of Monochamus alternatus against symbiotic and entomopathogenic fungi

Meng

Ning

et al. 2017

Sci. China Life Sci.

Self Cite

“…To investigate mRNA levels of T. xiaojinensis CTLDP genes, we searched their FPKM values in ten libraries (Meng et al ., ). The results are listed in Table S6.…”

Section: Resultsmentioning

confidence: 97%

“…After infection with C. militaris or E. cloacae , the larvae die within several days. However, O. sinensis can infect larvae for a long time, ranging from several months to 1 year (Meng et al ., ). As previously noted, IMLs probably play significant roles in binding a variety of microbes and activating immune responses in T. xiaojinensis .…”

Section: Discussionmentioning

confidence: 97%

Comparative analysis of C‐type lectin domain proteins in the ghost moth, Thitarodes xiaojinensis (Lepidoptera: Hepialidae)

Meng

et al. 2018

Insect Science

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Insects have a large family of C-type lectins involved in cell adhesion, pathogen recognition and activation of immune responses. In this study, 32 transcripts encoding C-type lectin domain proteins (CTLDPs) were identified from the Thitarodes xiaojinensis transcriptome. According to their domain structures, six CTLDPs with one carbohydrate-recognition domain (CRD) were classified into the CTL-S subfamily. The other 23 CTLDPs with two CRDs were grouped into the immulectin (IML) subfamily. The remaining three with extra regulatory domains were sorted into the CTL-X subfamily. Phylogenetic analysis showed that CTL-S and CTL-X members from different insects could form orthologous groups. In contrast, no T. xiaojinensis IML orthologues were found in other insects. Remarkable lineage-specific expansion in this subfamily was observed reflecting that these CTLDPs, as important receptors, have evolved diversified members in response to a variety of microbes. Prediction of binding ligands revealed that T. xiaojinensis, a cold-adapted species, conserved the ability of CRDs to combine with Ca to keep its receptors from freezing. Comparative analysis of induction of CTLDP genes after different immune challenges indicated that IMLs might play critical roles in immune defenses. This study examined T. xiaojinensis CTLDPs and provides a basis for further studies of their characteristics.

“…CTLs form a large family of sugar‐binding proteins that are involved in the innate immune response by recognizing polysaccharide chains on the surface of pathogens, including PPO activation, hemocyte nodule formation, opsonization and microbial clearance (Weis et al ., ; Meng et al ., ). Nine CTL sequences were identified in M. alternatus .…”

Section: Resultsmentioning

confidence: 97%

“…The amino acid sequences of known immunity‐related genes from other insect species, including Tribolium castaneum , Drosophila melanogaster , Bombyx mori , Anopheles gambiae , Aedes aegypti and Apis mellifera , retrieved from NCBI, Immunodb or Ensembl, were used as templates for a BlastX search of M. alternatus unigenes. Using the annotation above, the potential candidates of M. alternatus immunity‐related genes were confirmed manually (Meng et al ., ). In addition, domain analyses of the retrieved protein sequences were carried out by NCBI Conserve‐Domain Tool (https://www.ncbi.nlm.nih.gov/cdd), Pfam (http://www/sanger.ac.uk/Software/Pfam/), PROSITE (http://au.expasy.org/prosite/), SMART (http://smart.embl-heidelberg.de/) and InterPro (http://www.ebi.ac.uk/interpro/).…”

Section: Methodsmentioning

confidence: 97%

Comparative analysis of the Monochamus alternatus immune system

Zhou

et al. 2017

Insect Science

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The pine sawyer beetle, Monochamus alternatus, is regarded as a notorious forest pest in Asia, vectoring an invasive pathogenic nematode, Bursaphelenchus xylophilus, which is known to cause pine wilt disease. However, little sequence information is available for this vector beetle. This hampered the research on its immune system. Based on the transcriptome of M. alternatus, we have identified and characterized 194 immunity-related genes in M. alternatus, and compared them with homologues molecules from other species known to exhibit immune responses against invading microbes. The lower number of putative immunity-related genes in M. alternatus were attributed to fewer C-type lectin, serine protease (SP) and anti-microbial peptide (AMP) genes. Phylogenetic analysis revealed that M. alternatus had a unique recognition gene, galectin3, orthologues of which were not identified in Tribolium castaneum, Drosophila melanogastor, Anopheles gambiae and Apis mellifera. This suggested a lineage-specific gene evolution for coleopteran insects. Our study provides the comprehensive sequence resources of the immunity-related genes of M. alternatus, presenting valuable information for better understanding of the molecular mechanism of innate immunity processes in M. alternatus against B. xylophilus.