Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2015 Oct 26;16:867.
doi: 10.1186/s12864-015-2089-9.

Comparative Transcriptomic Analysis of Immune Responses of the Migratory Locust, Locusta Migratoria, to Challenge by the Fungal Insect Pathogen, Metarhizium Acridum

Affiliations
Free PMC article

Comparative Transcriptomic Analysis of Immune Responses of the Migratory Locust, Locusta Migratoria, to Challenge by the Fungal Insect Pathogen, Metarhizium Acridum

Wei Zhang et al. BMC Genomics. .
Free PMC article

Abstract

Background: The migratory locust, Locusta migratoria manilensis, is an immensely destructive agricultural pest that forms a devastating and voracious gregarious phase. The fungal insect pathogen, Metarhizium acridum, is a specialized locust pathogen that has been used as a potent mycoinsecticide for locust control. Little, however, is known about locust immune tissue, i.e. fat body and hemocyte, responses to challenge by this fungus.

Methods: RNA-seq (RNA sequencing) technology were applied to comparatively examine the different roles of locust fat body and hemocytes, the two major contributors to the insect immune response, in defense against M. acridum. According to the sequence identity to homologies of other species explored immune response genes, immune related unigenes were screened in all transcriptome wide range from locust and the differential expressed genes were identified in these two tissues, respectively.

Results: Analysis of differentially expressed locust genes revealed 4660 and 138 up-regulated, and 1647 and 23 down-regulated transcripts in the fat body and hemocytes, respectively after inoculation with M. acridum spores. GO (Gene Ontology) enrichment analysis showed membrane biogenesis related proteins and effector proteins significantly differentially expressed in hemocytes, while the expression of energy metabolism and development related transcripts were enriched in the fat body after fungal infection. A total of 470 immune related unigenes were identified, including members of the three major insect immune pathways, i.e. Toll, Imd (immune deficiency) and JAK/STAT (janus kinase/signal transduction and activator of transcription). Of these, 58 and three were differentially expressed in the insect fat body or hemocytes after infection, respectively. Of differential expressed transcripts post challenge, 43 were found in both the fat body and hemocytes, including the LmLys4 lysozyme, representing a microbial cell wall targeting enzyme.

Conclusions: These data indicate that locust fat body and hemocytes adopt different strategies in response to M. acridum infection. Fat body gene expression after M. acridum challenge appears to function mainly through activation of innate immune related genes, energy metabolism and development related genes. Hemocyte responses attempt to limit fungal infection primarily through regulation of membrane related genes and activation of cellular immune responses and release of humoral immune factors.

Figures

Fig. 1
Fig. 1
Summary of transcriptome analysis. a E-value distribution of BLAST hits for each unique sequence. b Similarity distribution of the top BLAST hits each sequence. c Species distribution shown as a percentage of the total homologous sequences with an E-value >e−25 using the first BLAST search hit for each sequence in the analysis
Fig. 2
Fig. 2
GO annotation of the overall unigene dataset. The total locust transcriptome dataset (9781 unigenes) were classified into biological process, cellular component, and molecular function subcategories
Fig. 3
Fig. 3
Analysis of clusters of orthologous groups of proteins (COGs). In all, 9781 unigenes were functionally grouped into the 25 COG categories and sub-catagories
Fig. 4
Fig. 4
GO classification of differential expressed genes (DEGs) in the locust fat body (a) and in hemocytes (b) after M. acridum infection
Fig. 5
Fig. 5
a Overlap between differentially expressed genes in the locust fat body and in hemocytes after M. acridum infection. b GO classification of fat body and hemocyte overlapping DEG dataset
Fig. 6
Fig. 6
Functional classification of fat body DEGs in response to M. acridum infection
Fig. 7
Fig. 7
Q-RT-PCR analysis of DEGs and comparison to transcriptomics data
Fig. 8
Fig. 8
Summary of the major immune related DEGs identified in the fat body and in hemocytes to be up regulated (red) and down regulated (black) after M. acridum infection

Similar articles

See all similar articles

Cited by 13 articles

See all "Cited by" articles

References

    1. Situation update: locust crisis in Madagascar FAO. [http://www.fao.org/fileadmin/user_upload/emergencies/docs/2014-05-08_MAG_Locust_Crisis_Situation_Update_EN.pdf].
    1. Nappi AJ, Ottaviani E. Cytotoxicity and cytotoxic molecules in invertebrates. Bioessays. 2000;22(5):469–480. doi: 10.1002/(SICI)1521-1878(200005)22:5<469::AID-BIES9>3.0.CO;2-4. - DOI - PubMed
    1. Tsakas S, Marmaras V. Insect immunity and its signalling: an overview. ISJ. 2010;7:228–238.
    1. Arrese EL, Soulages JL. Insect fat body: energy, metabolism, and regulation. Annu Rev Entomol. 2010;55:207. doi: 10.1146/annurev-ento-112408-085356. - DOI - PMC - PubMed
    1. Mirth CK, Riddiford LM. Size assessment and growth control: how adult size is determined in insects. Bioessays. 2007;29(4):344–355. doi: 10.1002/bies.20552. - DOI - PubMed

LinkOut - more resources

Feedback