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The discovery of the virulence gene ToxA in the wheat and barley pathogen Bipolaris sorokiniana.

ABSTRACT: Bipolaris sorokiniana is the causal agent of multiple diseases on wheat and barley and is the primary constraint to cereal production throughout South Asia. Despite its significance, the molecular basis of disease is poorly understood. To address this, the genomes of three Australian isolates of B. sorokiniana were sequenced and screened for known pathogenicity genes. Sequence analysis revealed that the isolate BRIP10943 harboured the ToxA gene, which has been associated previously with disease in the wheat pathogens Parastagonospora nodorum and Pyrenophora tritici-repentis. Analysis of the regions flanking ToxA within B. sorokiniana revealed that it was embedded within a 12-kb genomic element nearly identical to the corresponding regions in P. nodorum and P. tritici-repentis. A screen of 35 Australian B. sorokiniana isolates confirmed that ToxA was present in 12 isolates. Sequencing of the ToxA genes within these isolates revealed two haplotypes, which differed by a single non-synonymous nucleotide substitution. Pathogenicity assays showed that a B. sorokiniana isolate harbouring ToxA was more virulent on wheat lines that contained the sensitivity gene when compared with a non-ToxA isolate. This work demonstrates that proteins that confer host-specific virulence can be horizontally acquired across multiple species. This acquisition can dramatically increase the virulence of pathogenic strains on susceptible cultivars, which, in an agricultural setting, can have devastating economic and social impacts.

SUBMITTER: McDonald MC

PROVIDER: S-EPMC6638140 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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The discovery of the virulence gene ToxA in the wheat and barley pathogen Bipolaris sorokiniana.

McDonald Megan C MC Ahren Dag D Simpfendorfer Steven S Milgate Andrew A Solomon Peter S PS

Molecular plant pathology 20170312 2

Bipolaris sorokiniana is the causal agent of multiple diseases on wheat and barley and is the primary constraint to cereal production throughout South Asia. Despite its significance, the molecular basis of disease is poorly understood. To address this, the genomes of three Australian isolates of B. sorokiniana were sequenced and screened for known pathogenicity genes. Sequence analysis revealed that the isolate BRIP10943 harboured the ToxA gene, which has been associated previously with disease ...[more]

PMID: 28093843

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Project description:Mitogen-activated protein kinases (MAPKs) have been demonstrated to be involved in fungal development, sexual reproduction, pathogenicity and/or virulence in many filamentous plant pathogenic fungi, but genes for MAPKs in the fungal cereal pathogen Bipolaris sorokiniana have not been characterized. In this study, orthologues of three MAPK genes (CsSLT2, CsHOG1 and CsFUS3) and one MAPK kinase kinase (MAPKKK) gene (CsSTE11) were identified in the whole genome sequence of the B. sorokiniana isolate ND90Pr, and knockout mutants were generated for each of them. The ?Csfus3 and ?Csste11 mutants were defective in conidiation and formation of appressoria-like structures, showed hypersensitivity to oxidative stress and lost pathogenicity on non-wounded leaves of barley cv. Bowman. When inoculated on wounded leaves of Bowman, the ?Csfus3 and ?Csste11 mutants were reduced in virulence compared to the wild type. No morphological changes were observed in the ?Cshog1 mutants in comparison with the wild type; however, they were slightly reduced in growth under oxidative stress and were hypersensitive to hyperosmotic stress. The ?Cshog1 mutants formed normal appressoria-like structures but were reduced in virulence when inoculated on Bowman leaves. The ?Csslt2 mutants produced more vegetative hyphae, had lighter pigmentation, were more sensitive to cell wall degrading enzymes, and were reduced in virulence on Bowman leaves, although they formed normal appressoria like the wild type. Root infection assays indicated that the ?Cshog1 and ?Csslt2 mutants were able to infect barley roots while the ?Csfus3 and ?Csste11 failed to cause any symptoms. However, no significant difference in virulence was observed for ?Cshog1 mutants while ?Csslt2 mutants showed significantly reduced virulence on barley roots in comparison with the wild type. Our results indicated that all of these MAPK and MAPKKK genes are involved in the regulation of fungal development under normal and stress conditions and required for full virulence on barley plants.

Dataset Information

The discovery of the virulence gene ToxA in the wheat and barley pathogen Bipolaris sorokiniana.

Publications

The discovery of the virulence gene ToxA in the wheat and barley pathogen Bipolaris sorokiniana.

Similar Datasets

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