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.

Movement of cytoplasmic hypovirulence agents in chestnut blight cankers

1992 ◽  
Vol 70 (3) ◽  
pp. 557-561 ◽  
Author(s):  
L. Shain ◽  
J. B. Miller
Keyword(s):  
Biological Control ◽  
Key Words ◽  
Cryphonectria Parasitica ◽  
Castanea Dentata ◽  
American Chestnut ◽  
Chestnut Blight ◽  
Typical Morphology ◽  
Natural Range ◽  
Hypovirulent Strain ◽  
Endothia Parasitica

Chestnut blight cankers, initiated with virulent methionine auxotrophic strains of Cryphonectria parasitica, were challenged by placing one or two discs of agar and mycelium of prototrophic hypovirulent strains at their base. Movement of hypovirulence agents was confirmed by recovery of an isolate that exhibited the typical morphology of the introduced hypovirulent strain on media with methionine but little or no growth on media without methionine. Cultures from bark showed that the hypovirulent agent moved through mycelium around the circumference of cankers within 3 weeks when the virulent and challenging hypovirulent were vegetatively compatible. Conversion of the mycelium in the canker interior proceeded more slowly. Conversion of mycelium also was delayed, but eventually occurred, when virulent and hypovirulent inocula differed in vegetative compatibility. Conidia, however, continued to yield virulent, methionine-requiring cultures up to 65 weeks after challenge, even though underlying bark frequently yielded hypovirulent, methionine-requiring cultures. This disinclination of hypovirulent agents to enter the asexual apparatus in cankers may contribute substantially to the observed ineffective dissemination of hypovirulence in the natural range of American chestnut. Exploitation of those hypovirulent agents that can enter conidia in cankers may enhance the biological control of chestnut blight by hypovirulence. Key words: biological control, Cryphonectria parasitica, Endothia parasitica, Castanea dentata.

scholarly journals New finds of Cryphonectria parasitica and the first record of chestnut blight on red oak Quercus rubra L. in the Czech Republic

2012 ◽  
Vol 51 (No. 6) ◽  
pp. 256-258 ◽  
Author(s):  
P. Haltofová ◽  
L. Jankovský ◽  
D. Palovčíková
Keyword(s):  
Czech Republic ◽  
Castanea Sativa ◽  
First Record ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Red Oak ◽  
The Czech Republic ◽  
Sweet Chestnut ◽  
New Localities ◽  
Endothia Parasitica

The causal agent of the chestnut blight, the fungus Cryphonectria parasitica (Murrill) M. E. Barr (syn. Endothia parasitica (Murrill) P. J. Anderson et H. W. Anderson), was found out at new localities in the Czech Republic. The chestnut blight was observed for the first time in the Czech Republic in 2002. Two new localities were discovered in southern Moravia in May and June 2004. The disease was identified both on the sweet chestnut (Castanea sativa Mill.) and on the red oak (Quercus rubraL.). Infected trees were treated according to the order of the State Phytosanitary Administration of the Czech Republic. 

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 Management of Chestnut Blight in Greece Using Hypovirulence and Silvicultural Interventions

Forests ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 492 ◽  
Author(s):  
Stephanos Diamandis
Keyword(s):  
Biological Control ◽  
Castanea Sativa ◽  
Pilot Project ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Sweet Chestnut ◽  
Central Greece ◽  
Clear Cutting ◽  
Castanea Sativa Mill ◽  
Nut Production

Sweet chestnut (Castanea sativa Mill.) is an important tree for Greece. The invasive fungus Cryphonectria parasitica, which causes chestnut blight, was first found in Central Greece in 1963. It has since spread all over the country, significantly reducing the national annual nut production. The increasing decline of forests and orchards due to the disease led to a project in 1995, which aimed at studying the feasibility of applying biological control. A prerequisite study of the existing vegetative compatibility types of the pathogen showed only four, and their distribution was mapped. A pilot project (1998–2000) that consisted of clear cutting heavily infected coppice stands and introducing hypovirulence to the remainder was implemented on Mt. Athos on a 7000 ha sweet chestnut forest. Two evaluations (in 2003 and 2011) revealed that hypovirulence was established in the sweet chestnut forests and spread more or less homogeneously. A nationwide project introducing hypovirulence to 29 counties was implemented in two, 3-yr-periods 2007–2009 (17 counties) and 2014–2016 (12 counties). The new evaluations showed that hypovirulence spread profoundly and forests and orchards started recovering. The appearance of natural hypovirulence cannot be predicted. Introduced hypovirulence and silvicultural interventions can be used to manage the disease. It is the responsibility of the forest/orchard manager to decide whether to wait for appearance of natural hypovirulence, or to introduce it for a faster decline in disease.

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 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 Biologische Bekämpfung des Kastanienrindenkrebses auf der Alpennordseite der Schweiz|Biological control of chestnut blight north of the Swiss Alps

2007 ◽  
Vol 158 (11) ◽  
pp. 342-348
Author(s):  
Ursula Heiniger
Keyword(s):  
Biological Control ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Swiss Alps ◽  
Chestnut Blight ◽  
Biologische Bekämpfung ◽  
Chestnut Blight Fungus ◽  
Low Rate

Since 1986 several isolated stands of chestnut (Castanea sativa) located north of the Swiss Alps have been infected with the chestnut blight fungus (Cryphonectria parasitica). At all sites (1–3), the diversity of the vegetative compatibility types was low. To control the disease, the hypovirus CHV1 was introduced at seventeen sites in five cantons. In total, 571 cankers were treated with local C. parasitica isolates containing CHV1. Re-inspection of the cankers one to two years after treatment demonstrated that the percentage of active cankers was significantly reduced in three cantons. Re-isolations of C. parasitica showed that the hypovirus persisted in 33% to 75% of the treated cankers and was disseminated to new cankers at a low rate. The difficulties and the potential of hypovirus treatment of small chestnut stands are discussed.

scholarly journals Role of Fresh Dead Wood in the Epidemiology and the Biological Control of the Chestnut Blight Fungus

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 430-438 ◽  
Author(s):  
Joana Beatrice Meyer ◽  
Loïc Chalmandrier ◽  
Fabio Fässler ◽  
Christopher Schefer ◽  
Daniel Rigling ◽  
...  
Keyword(s):  
Biological Control ◽  
Dead Wood ◽  
Biocontrol Agent ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
Study Sites ◽  
Cryphonectria Hypovirus

The invasive fungus Cryphonectria parasitica, the causal agent of chestnut blight, is able to survive and sporulate on the bark of fresh dead Castanea sativa wood for at least 2 years. Here, we experimentally investigated the role of fresh dead wood in the epidemiology of chestnut blight, specifically in the spread of the hyperparasitic virus Cryphonectria hypovirus 1, which acts as biocontrol agent of C. parasitica. A total of 152 artificially initiated, virulent bark cankers in four chestnut stands were treated with virus-infected asexual spores originating either from sporulating dead wood or from a spore suspension. Molecular markers for both the virus and the fungal carrier were used to examine the spread of the applied biocontrol virus. Fourteen months after treatment, 42 to 76% of the conidial spray-treated cankers and 50 to 60% of the cankers exposed to a sporulating dead stem had been virus infected by the applied hypovirulent conidia in all four study sites. Virus infection reduced canker expansion and promoted canker healing (callusing). Thus, fresh chestnut dead wood may play an important role in supporting the successful spread of natural hypovirulence in chestnut forests. Further, combined with the application of virus-infected conidial suspensions, it may help promote the establishment of artificially released hypoviruses in chestnut stands to control chestnut blight.

scholarly journals A Tannic Acid–Inducible and Hypoviral-Regulated Laccase3 Contributes to the Virulence of the Chestnut Blight Fungus Cryphonectria parasitica

2008 ◽  
Vol 21 (12) ◽  
pp. 1582-1590 ◽  
Author(s):  
Hea-Jong Chung ◽  
Bo-Ra Kwon ◽  
Jung-Mi Kim ◽  
Seung-Moon Park ◽  
Jong-Kun Park ◽  
...  
Keyword(s):  
Tannic Acid ◽  
Constitutive Expression ◽  
Morphological Characteristics ◽  
Fungal Growth ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Loss Of Function ◽  
Fungal Virulence ◽  
Chestnut Blight Fungus ◽  
Hypovirulent Strain

A new laccase gene (lac3) from the chestnut blight fungus Cryphonectria parasitica was induced by the presence of tannic acid, which is abundant in the bark of chestnut trees and is assumed to be one of the major barriers against pathogen infection. However, other commonly known laccase inducers, including ferulic acid, 2,5-xylidine, catechol, and pH, did not induce lac3 transcription. Moreover, the hypovirus modulated the induction of lac3 transcription, abolishing the transcriptional induction of the lac3 gene by tannic acid. A functional analysis of lac3 using a lac3-null mutant indicated that fungal growth and other morphological characteristics, including pigmentation and sporulation, were not affected. However, a virulence assay indicated that the loss of function of a tannic acid–inducible and hypoviral-regulated laccase resulted in reduced virulence without detectable changes in the morphological features. The constitutive expression of lac3 resulted in no significant differences in the necrotic lesions from those caused by the wild type, but its expression in the presence of the hypovirus led to larger lesions than those caused by the hypovirulent strain. These results suggest that the lac3 gene product may not be the only determinant of fungal virulence in chestnut trees but is an important factor.

scholarly journals Results of biological control of chestnut blight in Slovakia

2005 ◽  
Vol 86 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Gabriela Juhásová ◽  
Katarína Adamcíková ◽  
Cécile Robin
Keyword(s):  
Biological Control ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Health Condition ◽  
Chestnut Blight

The health condition of Castanea sativa in the Stiavnicko-krupinská region of Slovakia was evaluated and the incidence of the fungus Cryphonectria parasitica was noted. A total of 2274 trees were examined. The degree of injury was expressed on a scale varying from zero to five and an index of health condition, IHC, was calculated from these data. The values of IHC varied from 0.12 to 1.36. From 1992 to 1997, we treated 714 cankers using hypovirulent strains of C. parasitica obtained from INRA Clermont-Ferrand. Callusing was observed on 32.7% of the treated cankers.

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