Characterization of the chestnut blight canker and the localization and isolation of the pathogen Cryphonectria parasitica

1989 ◽  
Vol 67 (12) ◽  
pp. 3600-3607 ◽  
Author(s):  
Patricia S. McManus ◽  
Frank W. Ewers ◽  
Dennis W. Fulbright
Keyword(s):  
Transverse Section ◽  
Virulent Strain ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Growth Rings ◽  
Double Stranded Rna ◽  
Naturally Occurring ◽  
Xylem Tissue ◽  
Hypovirulent Strain

Naturally occurring chestnut blight cankers on Castanea dentata were categorized as virulent (sunken bark with abundant stromata) or hypovirulent (swollen bark lacking stromata). In transverse section, xylem tissue of virulent cankers was discolored and largely nonconductive. Hypovirulent cankers had anomalous secondary xylem tissue that was light in color and conducted safranin dye, although xylem of the main stem axes of hypovirulent cankers was discolored. In naturally occurring cankers, no correlation was found between canker morphology and the presence or absence of double-stranded RNA in the inciting fungus (Cryphonectria parasitica). However, a virulent strain lacking double-stranded RNA induced cankers that resembled natural virulent cankers, and inoculation with a known hypovirulent strain containing double-stranded RNA resulted in swollen cankers that resembled natural hypovirulent cankers. Cryphonectria parasitica was isolated from all growth rings of virulent cankers and from the discolored xylem tissue of hypovirulent cankers but not from the conductive anomalous xylem tissue of hypovirulent cankers. Hyphae were observed via fluorescence microscopy in the xylem of natural and induced virulent cankers but not in hypovirulent cankers, whether natural or induced by artificial means.

scholarly journals The Morphology and the Biological Control of Cryphonectria parasitica

2012 ◽  
Vol 69 (1) ◽  
Author(s):  
Carmen Emilia PUIA ◽  
Daniela Andreea GRIGORESCU ◽  
Raluca Vasilica MICLEA
Keyword(s):  
Biological Control ◽  
Virulent Strain ◽  
Morphological Characteristics ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Dual Culture ◽  
Natural Form ◽  
Hypovirulent Strain ◽  
Endothia Parasitica

Cryphonectria parasitica  (Murr.) Bar [syn. Endothia parasitica (Murr. And.] (anamorf: Endothiella sp .) is the causal agent of chestnut bark disease or chestnut blight, disease which produced great damages throughout the world, for example, in Europe, the European chestnut tree ( Castanea sativa (P.) Mill) was heavily affected. Environmental concerns have focused attention on natural forms of disease control as an effective alternative to chemical pesticides. In the chestnut blight fungus, Cryphonectria parasitica deals with a natural form of biological control in which the virulence of a fungal pathogen is attenuated by an endogenous viral RNA genetic element- the hypovirulent strain. In our researches we picked samples of chestnut bark from different areas in Maramures county. We’ve isolated the fungus on PDA medium and we’ve studied the morphological characteristics of the usual virulent strain and we looked for a possible hypovirulent strain in order to study its capacity for biological control. The fungus develops in the bark and in cambium where forms a yellowish or brownish stroma and produces both conidia and ascospores. The pycnidia stromata break through the lenticels producing conidia and later in the same stroma develop the perithecia which produce ascospores. Both strains of the fungus were found in the research area. The hypovirulent strain had a slower development, showed no sporu lation and pigmentation “white cultural strain” and was tested in vitro for the capacity to convert the virulent isolates by dual culture tests.

scholarly journals Characterization of Hypovirus-Derived Small RNAs Generated in the Chestnut Blight Fungus by an Inducible DCL-2-Dependent Pathway

2008 ◽  
Vol 82 (6) ◽  
pp. 2613-2619 ◽  
Author(s):  
Xuemin Zhang ◽  
Gert C. Segers ◽  
Qihong Sun ◽  
Fuyou Deng ◽  
Donald L. Nuss
Keyword(s):  
Small Rnas ◽  
Rna Silencing ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Fungal Host ◽  
Chestnut Blight Fungus ◽  
Mutant Strains ◽  
Suppressor Of Rna Silencing ◽  
Dependent Pathway

ABSTRACT The disruption of one of two dicer genes, dcl-2, of the chestnut blight fungus Cryphonectria parasitica was recently shown to increase susceptibility to mycovirus infection (G. C. Segers, X. Zhang, F. Deng, Q. Sun, and D. L. Nuss, Proc. Natl. Acad. Sci. USA 104:12902-12906, 2007). We now report the accumulation of virus-derived small RNAs (vsRNAs) in hypovirus CHV1-EP713-infected wild-type and dicer gene dcl-1 mutant C. parasitica strains but not in hypovirus-infected dcl-2 mutant and dcl-1 dcl-2 double-mutant strains. The CHV1-EP713 vsRNAs were produced from both the positive and negative viral RNA strands at a ratio of 3:2 in a nonrandom distribution along the viral genome. We also show that C. parasitica responds to hypovirus and mycoreovirus infections with a significant increase (12- to 20-fold) in dcl-2 expression while the expression of dcl-1 is increased only modestly (2-fold). The expression of dcl-2 is further increased (∼35-fold) following infection with a hypovirus CHV1-EP713 mutant that lacks the p29 suppressor of RNA silencing. The combined results demonstrate the biogenesis of mycovirus-derived small RNAs in a fungal host through the action of a specific dicer gene, dcl-2. They also reveal that dcl-2 expression is significantly induced in response to mycovirus infection by a mechanism that appears to be repressed by the hypovirus-encoded p29 suppressor of RNA silencing.

scholarly journals Complete genome sequence of Mycoreovirus-1/Cp9B21, a member of a novel genus within the family Reoviridae, isolated from the chestnut blight fungus Cryphonectria parasitica

2004 ◽  
Vol 85 (11) ◽  
pp. 3437-3448 ◽  
Author(s):  
Nobuhiro Suzuki ◽  
S. Supyani ◽  
Kazuyuki Maruyama ◽  
Bradley I. Hillman
Keyword(s):  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Virus Family ◽  
Chestnut Blight Fungus ◽  
Choice Pattern ◽  
The Family ◽  
Isoelectric Points ◽  
Large Virus ◽  
Hypovirulent Strain ◽  
Cap Analysis

Mycoreovirus 1 (MYRV-1) is the type species of the newly described genus Mycoreovirus of the large virus family Reoviridae. The virus was isolated from a hypovirulent strain (9B21) of the chestnut blight fungus, Cryphonectria parasitica. A previous study showed that double-shelled particles introduced to fungal spheroplasts resulted in stably infected colonies. Of the 11 double-stranded RNA genomic segments (S1–S11), the three largest (S1–S3) were sequenced previously and shown to have moderate levels of similarity to the homologous segments of mammal-pathogenic coltiviruses (Eyach virus and Colorado tick fever virus) and another fungus-infecting reovirus, Mycoreovirus 3 of Rosellinia necatrix strain W370 (MYRV-3/RnW370). The sequences of the remaining segments (S4–S11) are reported here. All of the segments have single ORFs on their positive strands and the terminal sequences 5′-GAUCA----GCAGUCA-3′ are conserved among currently and previously sequenced segments. Oligo-cap analysis showed that the positive strands of the genomic segments are capped, whereas the negative strands are not. Similarities among the four evolutionarily related viruses include low or moderate levels of amino acid sequence identity (14·7–34·2 %) and isoelectric points among equivalent polypeptides, e.g. proteins encoded by segments S4 and S5 of the four viruses. Phylogenetic analysis indicated that MYRV-1/Cp9B21 is related more closely to MYRV-3/RnW370 than to the coltiviruses. An interesting dissimilarity is found in codon-choice pattern among the four viruses, i.e. MYRV-1/Cp9B21 segments have a lower frequency of [XYG+XYC] than corresponding segments of the other viruses, suggesting a possible adjustment of virus codon usage to their host environments.

scholarly journals Cutinase in Cryphonectria parasitica, the chestnut blight fungus: suppression of cutinase gene expression in isogenic hypovirulent strains containing double-stranded RNAs.

1992 ◽  
Vol 12 (10) ◽  
pp. 4539-4544 ◽  
Author(s):  
D A Varley ◽  
G K Podila ◽  
S T Hiremath
Keyword(s):  
Gene Expression ◽  
Fusarium Solani ◽  
Virulent Strain ◽  
Pathogenic Fungi ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Plant Pathogenic Fungi ◽  
Chestnut Blight Fungus ◽  
Plant Cuticles ◽  
Isogenic Strains

Plant-pathogenic fungi produce cutinase, an enzyme required to degrade plant cuticles and facilitate penetration into the host. The absence of cutinase or a decrease in its production has been associated with a decrease in pathogenicity of the fungus. A set of isogenic strains of Cryphonectria parasitica, the chestnut blight fungus, was tested for the presence and amounts of cutinase activity. The virulent strain of C. parasitica produced and secreted significantly higher amounts of cutinase than the hypovirulent strains. Use of both nucleic acid and polyclonal antibody probes for cutinase from Fusarium solani f. sp. pisi showed that cutinase in C. parasitica is 25 kDa in size and is coded by a 1.1-kb mRNA. Both mRNA and protein were inducible by cutin hydrolysate, while hypovirulence agents suppressed the level of mRNA and the enzyme. Since all the strains had the cutinase gene, the suppression of expression was due to the hypovirulence agents. The data presented are the first report indicating that hypovirulence agents in C. parasitica regulate a gene associated with pathogenicity in other plant-pathogenic fungi.

Virus-like particles in hyphae and conidia of European hypovirulent (dsRNA-containing) strains of Cryphonectria parasitica

1990 ◽  
Vol 68 (1) ◽  
pp. 90-101 ◽  
Author(s):  
Joseph R. Newhouse ◽  
William L. MacDonald ◽  
Harvey C. Hoch
Keyword(s):  
Defense Response ◽  
Lipid Membrane ◽  
Virulent Strain ◽  
Lipid Extraction ◽  
Staining Technique ◽  
Cryphonectria Parasitica ◽  
Fungal Host ◽  
Virus Like Particles ◽  
Hypovirulent Strain ◽  
Endothia Parasitica

Hyphae and germinating conidia of European hypovirulent (dsRNA-containing) Cryphonectria parasitica strain Ep-50 and virulent (dsRNA-free) strain Ep-67 (isogenic derivative from Ep-50), and hyphae only of European hypovirulent (dsRNA-containing) strains Ep-4 and Euro-7 were freeze-substituted and examined for the presence of virus-like particles (VLPs) using transmission electron microscopy. Spherical, membrane-bounded VLPs, measuring 50–90 nm in diameter, were located in hyphae and conidia of hypovirulent strain Ep-50, but not virulent strain Ep-67. Hyphae of hypovirulent strains Ep-4 and Euro-7 contained VLPs similar to those found in Ep-50. The VLPs occurred in aggregates surrounded by rough endoplasmic reticulum or more rarely, scattered throughout the cytoplasm; most possessed an electron-dense core. Results of Bernhard's regressive staining technique and lipid extraction cytochemistry suggested that the particles consisted of RNA surrounded by a lipid membrane. A unique Golgi body was associated with the formation of VLPs in hypovirulent strain Ep-50. The VLPs do not resemble typical fungal viruses and may be the end product of a defense response on the part of the fungal host designed to wall off foreign nucleic acid. Key words: Endothia parasitica, mycovirus, defense response, hypovirulence, viroid, fungal Golgi.

scholarly journals Biological control of sweet chestnut on Pécsbánya, Hungary

2018 ◽  
pp. 77-81
Author(s):  
Gabriella Kovács ◽  
Dominika Bodnár ◽  
Gábor Tarcali ◽  
László Radócz
Keyword(s):  
Biological Control ◽  
Biological Process ◽  
Cryphonectria Parasitica ◽  
Plant Health ◽  
Chestnut Blight ◽  
Gall Wasp ◽  
Sweet Chestnut ◽  
Dryocosmus Kuriphilus ◽  
Hypovirulent Strain ◽  
Blight Disease

The supervision of plant hygiene of sweet chestnut grove on Pécsbánya (South Hungary) started more than four years ago. Hypovirulent strains were applied as a biological process to control Cryphonectria parasitica fungus which causes the chestnut blight disease. By now the performed interventions have shown obvious results, the vitality of the trees has greatly improved, the amount of harvested nuts is increasing, and the hypovirulent strain has been spreading within the area. During plant health inspection the galls of chestnut gall wasp (Dryocosmus kuriphilus) was found in the year of 2015, which is the obvious symptom of new occurrence of the pest. The pest was eradicated by destroy galls, which allows taking out of consideration the damage by now in this area.

scholarly journals Hypovirus-Responsive Transcription Factor Gene pro1 of the Chestnut Blight Fungus Cryphonectria parasitica Is Required for Female Fertility, Asexual Spore Development, and Stable Maintenance of Hypovirus Infection

2008 ◽  
Vol 8 (3) ◽  
pp. 262-270 ◽  
Author(s):  
Qihong Sun ◽  
Gil H. Choi ◽  
Donald L. Nuss
Keyword(s):  
Transcription Factor ◽  
Cryphonectria Parasitica ◽  
Female Fertility ◽  
Chestnut Blight ◽  
Transcription Factor Gene ◽  
Factor Gene ◽  
Disruption Mutant ◽  
Chestnut Blight Fungus ◽  
Stable Maintenance

ABSTRACT We report characterization of the gene encoding putative transcription factor PRO1, identified in transcriptional profiling studies as being downregulated in the chestnut blight fungus Cryphonectria parasitica in response to infection by virulence-attenuating hypoviruses. Sequence analysis confirmed that pro1 encodes a Zn(II)2Cys6 binuclear cluster DNA binding protein with significant sequence similarity to the pro1 gene product that controls fruiting body development in Sordaria macrospora. Targeted disruption of the C. parasitica pro1 gene resulted in two phenotypic changes that also accompany hypovirus infection, a significant reduction in asexual sporulation that could be reversed by exposure to high light intensity, and loss of female fertility. The pro1 disruption mutant, however, retained full virulence. Although hypovirus CHV1-EP713 infection was established in the pro1 disruption mutant, infected colonies continually produced virus-free sectors, suggesting that PRO1 is required for stable maintenance of hypovirus infection. These results complement the recent characterization of the hypovirus-responsive homologue of the Saccharomyces cerevisiae Ste12 C2H2 zinc finger transcription factor gene, cpst12, which was shown to be required for C. parasitica female fertility and virulence.

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