Dataset Information

Genome sequencing and comparative transcriptomics of the model entomopathogenic fungi Metarhizium anisopliae and M. acridum.

ABSTRACT: Metarhizium spp. are being used as environmentally friendly alternatives to chemical insecticides, as model systems for studying insect-fungus interactions, and as a resource of genes for biotechnology. We present a comparative analysis of the genome sequences of the broad-spectrum insect pathogen Metarhizium anisopliae and the acridid-specific M. acridum. Whole-genome analyses indicate that the genome structures of these two species are highly syntenic and suggest that the genus Metarhizium evolved from plant endophytes or pathogens. Both M. anisopliae and M. acridum have a strikingly larger proportion of genes encoding secreted proteins than other fungi, while ~30% of these have no functionally characterized homologs, suggesting hitherto unsuspected interactions between fungal pathogens and insects. The analysis of transposase genes provided evidence of repeat-induced point mutations occurring in M. acridum but not in M. anisopliae. With the help of pathogen-host interaction gene database, ~16% of Metarhizium genes were identified that are similar to experimentally verified genes involved in pathogenicity in other fungi, particularly plant pathogens. However, relative to M. acridum, M. anisopliae has evolved with many expanded gene families of proteases, chitinases, cytochrome P450s, polyketide synthases, and nonribosomal peptide synthetases for cuticle-degradation, detoxification, and toxin biosynthesis that may facilitate its ability to adapt to heterogeneous environments. Transcriptional analysis of both fungi during early infection processes provided further insights into the genes and pathways involved in infectivity and specificity. Of particular note, M. acridum transcribed distinct G-protein coupled receptors on cuticles from locusts (the natural hosts) and cockroaches, whereas M. anisopliae transcribed the same receptor on both hosts. This study will facilitate the identification of virulence genes and the development of improved biocontrol strains with customized properties.

SUBMITTER: Gao Q

PROVIDER: S-EPMC3017113 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Genome sequencing and comparative transcriptomics of the model entomopathogenic fungi Metarhizium anisopliae and M. acridum.

Gao Qiang Q Jin Kai K Ying Sheng-Hua SH Zhang Yongjun Y Xiao Guohua G Shang Yanfang Y Duan Zhibing Z Hu Xiao X Xie Xue-Qin XQ Zhou Gang G Peng Guoxiong G Luo Zhibing Z Huang Wei W Wang Bing B Fang Weiguo W Wang Sibao S Zhong Yi Y Ma Li-Jun LJ St Leger Raymond J RJ Zhao Guo-Ping GP Pei Yan Y Feng Ming-Guang MG Xia Yuxian Y Wang Chengshu C

PLoS genetics 20110106 1

Metarhizium spp. are being used as environmentally friendly alternatives to chemical insecticides, as model systems for studying insect-fungus interactions, and as a resource of genes for biotechnology. We present a comparative analysis of the genome sequences of the broad-spectrum insect pathogen Metarhizium anisopliae and the acridid-specific M. acridum. Whole-genome analyses indicate that the genome structures of these two species are highly syntenic and suggest that the genus Metarhizium evo ...[more]

PMID: 21253567

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Project description:BACKGROUND: Metarhizium anisopliae is an important fungal biocontrol agent of insect pests of agricultural crops. Genomics can aid the successful commercialization of biopesticides by identification of key genes differentiating closely related species, selection of virulent microbial isolates which are amenable to industrial scale production and formulation and through the reduction of phenotypic variability. The genome of Metarhizium isolate ARSEF23 was recently published as a model for M. anisopliae, however phylogenetic analysis has since re-classified this isolate as M. robertsii. We present a new annotated genome sequence of M. anisopliae (isolate Ma69) and whole genome comparison to M. robertsii (ARSEF23) and M. acridum (CQMa 102). RESULTS: Whole genome analysis of M. anisopliae indicates significant macrosynteny with M. robertsii but with some large genomic inversions. In comparison to M. acridum, the genome of M. anisopliae shares lower sequence homology. While alignments overall are co-linear, the genome of M. acridum is not contiguous enough to conclusively observe macrosynteny. Mating type gene analysis revealed both MAT1-1 and MAT1-2 genes present in M. anisopliae suggesting putative homothallism, despite having no known teleomorph, in contrast with the putatively heterothallic M. acridum isolate CQMa 102 (MAT1-2) and M. robertsii isolate ARSEF23 (altered MAT1-1). Repetitive DNA and RIP analysis revealed M. acridum to have twice the repetitive content of the other two species and M. anisopliae to be five times more RIP affected than M. robertsii. We also present an initial bioinformatic survey of candidate pathogenicity genes in M. anisopliae. CONCLUSIONS: The annotated genome of M. anisopliae is an important resource for the identification of virulence genes specific to M. anisopliae and development of species- and strain- specific assays. New insight into the possibility of homothallism and RIP affectedness has important implications for the development of M. anisopliae as a biopesticide as it may indicate the potential for greater inherent diversity in this species than the other species. This could present opportunities to select isolates with unique combinations of pathogenicity factors, or it may point to instability in the species, a negative attribute in a biopesticide.

Project description:Transcript patterns elicited in response to hosts can reveal how fungi recognize suitable hosts and the mechanisms involved in pathogenicity. These patterns could be fashioned by recognition of host-specific topographical features or by chemical components displayed or released by the host. We investigated this in the specific locust pathogen Metarhizium anisopliae var. acridum. Only host (Schistocerca gregaria) cuticle stimulated the full developmental program of germination and differentiation of infection structures (appressoria). Cuticle from beetles (Leptinotarsa decimlineata) repressed germination while cuticle from hemipteran bugs (Magicicada septendecim) allowed germination but only very low levels of differentiation, indicating that the ability to cause disease can be blocked at different stages. Using organic solvents to extract insects we identified a polar fraction from locusts that allowed appressorial formation against a flat plastic (hydrophobic) surface. Microarrays comprising 1,730 expressed sequence tags were used to determine if this extract elicits different transcriptional programs than whole locust cuticle or nonhost extracts. Of 483 differentially regulated genes, 97% were upregulated. These included genes involved in metabolism, utilization of host cuticle components, cell survival and detoxification, and signal transduction. Surprisingly, given the complex nature of insect epicuticle components and the specific response of M. anisopliae var. acridum to locusts, very similar transcript profiles were observed on locust and beetle extracts. However, the beetle extract cluster was enriched in genes for detoxification and redox processes, while the locust extract upregulated more genes for cell division and accumulation of cell mass. In addition, several signal transduction genes previously implicated in pathogenicity in plant pathogens were only upregulated in response to locust extract, implying similarities in the regulatory circuitry of these pathogens with very different hosts.

Dataset Information

Genome sequencing and comparative transcriptomics of the model entomopathogenic fungi Metarhizium anisopliae and M. acridum.

Publications

Genome sequencing and comparative transcriptomics of the model entomopathogenic fungi Metarhizium anisopliae and M. acridum.

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