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MrHex1 is Required for Woronin Body Formation, Fungal Development and Virulence in Metarhizium robertsii.

ABSTRACT: The Woronin body (WB) is a peroxisome-derived dense-core vesicle, a self-assembling hexagonal crystal of a single protein Hex1. This organelle is specific to the ascomycete fungi belonging to the Pezizomycotina subphylum by functioning in sealing septal pores in response to mycelium damage and the control of cell heterogeneity. We retrieved all available Hex1-domain containing proteins of different fungi from the GenBank database and found considerable length variations among 460 obtained Hex1 proteins. However, a highly conserved Hex1 domain containing 75 amino acid residues with a specific S/A-R/S-L consensus motif for targeting peroxisome is present at the carboxy-terminus of each protein. A homologous Hex1 gene, named MrHex1, was deleted in the entomopathogenic fungus Metarhizium robertsii. It was found that MrHex1 was responsible for WB formation in M. robertsii and involved in sealing septal pores to maintain cell integrity and heterogeneity. Different assays indicated that, relative to the wild-type (WT) strain, ?Mrhex1 demonstrated a growth defect on a solid medium and substantial reductions of conidiation, appressorium formation and topical infectivity against insect hosts. However, there was no obvious virulence difference between WT and mutants during injection of insects. We also found that ?MrHex1 could tolerate different stress conditions like the WT and the gene-rescued mutant of M. robertsii, which is in contrast to the reports of the stress-response defects of the Hex1 null mutants of other fungal species. In addition to revealing the phenotypic/functional alterations of the Hex1 deletion mutants between different pathotype fungi, the results of this study may benefit the understanding of the evolution and WB-control of fungal entomopathogenicity.

SUBMITTER: Tang G

PROVIDER: S-EPMC7559983 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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MrHex1 is Required for Woronin Body Formation, Fungal Development and Virulence in <i>Metarhizium robertsii</i>.

Tang Guirong G Shang Yanfang Y Li Shiqing S Wang Chengshu C

Journal of fungi (Basel, Switzerland) 20200914 3

The Woronin body (WB) is a peroxisome-derived dense-core vesicle, a self-assembling hexagonal crystal of a single protein Hex1. This organelle is specific to the ascomycete fungi belonging to the Pezizomycotina subphylum by functioning in sealing septal pores in response to mycelium damage and the control of cell heterogeneity. We retrieved all available Hex1-domain containing proteins of different fungi from the GenBank database and found considerable length variations among 460 obtained Hex1 p ...[more]

PMID: 32937856

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Project description:BACKGROUND:Metarhizium robertsii, a widely distributed insect pathogen, is presently used as a natural alternative to chemical insecticides. Unfortunately, its worldwide commercial use has been restricted by a short shelf life and inconsistencies in virulence. In our previous study, a gene (GenBank accession number EFZ01626) was found to be significantly upregulated in heat-treated conidia. In the present study, this gene was characterized via gene disruption and complementation strategies. RESULTS:The gene (amplified by rapid amplification of cDNA ends PCR) was 1219 bp long and contained an open reading frame (ORF) of 777 bp. It encoded a protein of 234 amino acid residues with a 26-residue signal peptide. Bioinformatics analyses did not identify conserved functional domains; therefore, it was assumed to be a secreted virulence-associated protein according to its signal peptide and bioassay results. We found that the conidial germination rate of the ΔMrSVP mutant fungi dramatically decreased after heat shock treatment in a thermotolerance test. In addition, transcription levels of all tested heat shock-related genes were significantly lower in the mutant than in the wild type. We also demonstrated that the mean lethal time to death (LT50) of ΔMrSVP significantly increased relative to the wild type in insect bioassays (both topical inoculation and injection) involving Galleria mellonella. Moreover, similar rates of appressorium formation between ΔMrSVP and the wild type-and the significantly different expression of virulence-related genes such as acid trehalase and sucrose nonfermenting protein kinase in the haemocoel after injection-revealed that MrSVP is required for virulence in the insect haemocoel. CONCLUSIONS:Overall, our data suggest that the Mrsvp gene contributes to thermotolerance and virulence of M. robertsii. Furthermore, this gene is deeply involved in the mycosis of insect cadavers and in immune escape rather than insect cuticle penetration during infection.

Dataset Information

MrHex1 is Required for Woronin Body Formation, Fungal Development and Virulence in Metarhizium robertsii.

Publications

MrHex1 is Required for Woronin Body Formation, Fungal Development and Virulence in <i>Metarhizium robertsii</i>.

Similar Datasets

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