A Rapid Method for Testing the Virulence of<i>Cryphonectria parasitica</i>Using Excised Bark and Wood of American Chestnut

Lee, J. K.; Tattar, Terry A.; Berman, Phyllis; Mount, Mark S.

doi:10.1094/phyto-82-1454

Cited by 34 publications

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“…Culture conditions were as described by Kim et al (1995). To determine the canker area, 5-mm agar plugs containing mycelium were placed on excised bark and the resulting canker areas were measured 7 days after inoculation as described previously (Lee et al, 1992). The data are the means±SD of replicates from at least two trials of each virulence test per strain.…”

Section: Discussionmentioning

confidence: 99%

“…Pathogenicity tests performed using bark excised from a chestnut tree (Lee et al, 1992) indicated that the cpmk2 mutant is less virulent than EP155/2 ( Table 1). The size of the necrotic area induced on excised bark by the cpmk2 mutant was even smaller than that of a hypovirulent strain, indicating that the cpmk2 loss-of-function mutant resulted in a significant decrease in virulence, even more severe than that of CHV1-EP713.…”

Section: Laccase Activity and Virulence Assaysmentioning

confidence: 99%

“…Phenotypic changes in pigmentation, conidiation and mating capability were measured as described previously (Kim et al, 1995;Park et al, 2004). A virulence test using excised chestnut tree bark was conducted according to Lee et al (1992). Laccase activity was gauged by growing the strains on Bavendamm's medium (0?05 % tannic acid, 1?5 % malt extract, 2?0 % agar) and assessing the resulting colouration of the medium (Rigling et al, 1989).…”

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confidence: 99%

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Characterization of the ERK homologue CpMK2 from the chestnut blight fungus Cryphonectria parasitica

et al. 2005

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The Cryphonectria parasitica gene cpmk2, which encodes a mitogen-activated protein kinase belonging to the yeast extracellular signalling-regulated kinase (YERK1) subfamily, was isolated and its biological function was examined. Disruption of cpmk2 resulted in impaired pigmentation and abolished conidiation. Growth defects were observed in the cpmk2 mutant grown on solid plates, but growth of the mutant appeared normal in liquid media, including EP complete and PD broth, suggesting that the cpmk2 gene is involved in sensing and responding to growth conditions. The mutant's production of laccase, as measured by the size of the coloured area produced on tannic-acid-supplemented plates, was significantly reduced compared with the wild-type, but the intensity of the coloured area was unchanged, suggesting that the reduced laccase activity was owing to reduced growth on solid media rather than transcriptional downregulation. A dramatic reduction observed in the canker area produced by the cpmk2 mutant compared with the wild-type, even more severe than that of a hypovirulent strain, can also be ascribed to defective growth on solid surfaces rather than to impairments in a virulence factor(s). Downregulation of the pheromone gene Mf2/1 was also observed in the mutant, indicating a possible explanation for the regulation of the pheromone precursor gene in filamentous fungi and suggesting the presence of the yeast-like pheromone-responsive pathway in C. parasitica. Immunoblot analyses revealed that the phosphorylation level of CpMK2 increased in both virus-free and virus-containing strains in liquid cultures of up to 5 days old and decreased in older cultures. Moreover, the CpMK2 phosphorylation level increased in both strains after transfer from liquid to solid medium. However, levels of phosphorylated CpMK2 were similar in the two strains, suggesting that CpMK2, unlike CpMK1, is not under the direct control of a hypovirus.

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Section: Discussionmentioning

confidence: 99%

Section: Laccase Activity and Virulence Assaysmentioning

confidence: 99%

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confidence: 99%

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Characterization of the ERK homologue CpMK2 from the chestnut blight fungus Cryphonectria parasitica

et al. 2005

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“…The bark/wood assay described by Lee et al (1992) was used to determine the relative virulence of selected isolates. The assays were performed essentially as described, except that bark lesions only (not wood) were measured.…”

Section: Virulence Assaysmentioning

confidence: 99%

Movement of a small mitochondrial double-stranded RNA element of Cryphonectria parasitica: ascospore inheritance and implications for mitochondrial recombination

1997

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Movement via somatic fusion and inheritance of a small mitochondrial double-stranded (ds) RNA element was examined in Cryphonectria parasitica. The 2.7-kb dsRNA from the C. parasitica strain NB631 encodes a putative RNA-dependent RNA polymerase when the mitochondrial code (UGA = Trp) is invoked. All progeny from asexual spores (conidia) of strain NB631 examined for dsRNA contained the 2.7-kb element. Unlike other C. parasitica dsRNAs, which are cytoplasmic, the dsRNA in strain NB631 was transmitted through the sexual cycle (ascospores) if the strain containing the element acted as the female in crosses. Movement of the 2.7-kb dsRNA was also observed through hyphal anastomosis. Transfer by anastomosis was accompanied by mitochondrial movement and recombination of the mitochondrial genome as determined by RFLP analysis. In control pairings between isolates lacking dsRNA, mitochondrial movement and recombination were also observed. Transfer by anastomosis allowed the generation of infected and uninfected isogenic lines, and permitted us to evaluate the effects of the dsRNA element on virulence of the host. Bark virulence assays on American chestnut suggest that NB631 dsRNA decreases the virulence of C. parasitica, but not to the level associated with members of the Hypoviridae.

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“…Virulence test methods are an important means to investigate phytopathogenic fungi and therefore the development of these methods is a continuous effort (see, for example, in Cryphonectria parasitica [5]). To study and evaluate C. heterostrophus strains virulence, an accurate, sensitive, rapid, convenient and reproducible pathogenicity test is critical.…”

Section: Introductionmentioning

confidence: 99%

Pathogenicity Assay for <i>Cochliobolus heterostrophus</i> G-Protein and MAPK Signaling Deficiency Strains

Degani¹

2014

AJPS

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Cochliobolus heterostrophus is an agriculturally important and emerging model pathogen for studying the signaling hierarchies' role during the maize host colonization. In particular, G-protein and MAPK-linked pathways are playing a major role during pathogenesis. Although gene disruption studies are an efficient way of identifying the role of these cascades, differentiating between the mutant strains' virulence ability may become an intricate task. For example, in C. heterostrophus, mutants in a G-protein α subunit gene, cga1, are defective in mating and appressorium formation, but unlike mutants in homologous genes in other fungal pathogens, the cga1 mutants remained highly virulent to corn under some host physiological conditions. Here, we used the cga1 strain as a model for developing an in vivo sensitive and accurate pathogenicity assay. A detailed and well controlled analysis of wild type (WT) and cga1 pathogenic behavior revealed that detached leaves are significantly more vulnerable to the disease than intact ones. In intact leaves, cga1 mutants were less infective of maize under most conditions. This difference was maximized when the first seedling leaf was chosen for inoculation and when the infected leaves, with spores or mycelia fragments droplets, were incubated for a period of four days. This optimal condition set enabled us to classify the C. heterostrophus G-protein signaling mutants deficient in α, β or both subunits in order of decreasing virulence: WT > cga1> cgb1> cga1 cgb1. The method presented proved to be accurate and sensitive enough to identify even slight variations in virulence. Moreover, it could be modified for use in studies of other foliar phytoparasitic fungi.

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A Rapid Method for Testing the Virulence ofCryphonectria parasiticaUsing Excised Bark and Wood of American Chestnut

Cited by 34 publications

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Characterization of the ERK homologue CpMK2 from the chestnut blight fungus Cryphonectria parasitica

Characterization of the ERK homologue CpMK2 from the chestnut blight fungus Cryphonectria parasitica

Movement of a small mitochondrial double-stranded RNA element of Cryphonectria parasitica: ascospore inheritance and implications for mitochondrial recombination

Pathogenicity Assay for <i>Cochliobolus heterostrophus</i> G-Protein and MAPK Signaling Deficiency Strains

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A Rapid Method for Testing the Virulence ofCryphonectria parasiticaUsing Excised Bark and Wood of American Chestnut

Cited by 34 publications

References 0 publications

Characterization of the ERK homologue CpMK2 from the chestnut blight fungus Cryphonectria parasitica

Characterization of the ERK homologue CpMK2 from the chestnut blight fungus Cryphonectria parasitica

Movement of a small mitochondrial double-stranded RNA element of Cryphonectria parasitica: ascospore inheritance and implications for mitochondrial recombination

Pathogenicity Assay for &lt;i&gt;Cochliobolus heterostrophus&lt;/i&gt; G-Protein and MAPK Signaling Deficiency Strains

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Pathogenicity Assay for <i>Cochliobolus heterostrophus</i> G-Protein and MAPK Signaling Deficiency Strains