scholarly journals Saprophytic Activity and Sporulation of Cryphonectria parasitica on Dead Chestnut Wood in Forests with Naturally Established Hypovirulence

2006 ◽  
Vol 96 (12) ◽  
pp. 1337-1344 ◽  
Author(s):  
S. Prospero ◽  
M. Conedera ◽  
U. Heiniger ◽  
D. Rigling
Keyword(s):  
Biological Control ◽  
Dead Wood ◽  
Transmission Rate ◽  
Virus Transmission ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
The Mean ◽  
Chestnut Wood

Sustainable biological control of the chestnut blight fungus Crypho-nectria parasitica with hypovirulence depends on the production and dissemination of hypovirus-infected propagules of the pathogen. We investigated the ability of C. parasitica to sporulate and produce hypo-virus-infected spores on recently dead chestnut wood in coppice stands in southern Switzerland where hypovirulence has been naturally established. The number and type (active, inactive, or none) of cankers was assessed on experimentally cut and stacked stems, firewood stacks, and natural dead wood. Hypovirus-free and hypovirus-infected strains readily survived for more than 1 year in the chestnut blight cankers of the stacked stems. Sporulation of C. parasitica was observed on the surface of preexisting inactive and active cankers, as well as on newly colonized bark areas and was significantly more abundant than on comparable cankers on living stems. On all types of dead wood, we observed more stromata with perithecia than with pycnidia; however, a large proportion of the stromata was not differentiated. All perithecia examined yielded only hypovirus-free ascospores. The incidence of pycnidia that produced hypovirus-infected conidia ranged from 5% on natural dead wood to 41% on the experimental stacks. The mean virus transmission rate into conidia was 69%. Our study demonstrates a considerable saprophytic activity of C. parasitica on recently dead chestnut wood and supports the hypothesis of a role of this saprophytic phase in the epidemiology of hypovirulence.

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 Modified small-scale batch procedure for isolation of dsRNA from Cryphonectria parasitica

2007 ◽  
Vol 88 (1) ◽  
pp. 27-29
Author(s):  
Jana Libantová ◽  
Jana Moravčíková ◽  
Katarína Adamčíková ◽  
Marek Kobza ◽  
Gabriela Juhásová
Keyword(s):  
Biological Control ◽  
Cost Savings ◽  
Cryphonectria Parasitica ◽  
Fungal Disease ◽  
Small Scale ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus

Cytoplasmically-transmissible viral double-stranded RNAs of the genus Hypovirus cause reduced virulence (hypovirulence) in the chestnut blight fungus Cryphonectria parasitica. Biological control of this fungal disease is done by inoculating selected artificial hypovirulent strains of C. parasitica in the wounds of attacked chestnut trees and is followed by testing the transmissibility of dsRNA to C. parasitica isolates affecting these trees. Here we present a modified protocol of isolation and detection of dsRNA. The proposed procedure requires smaller amounts of fungal material for dsRNA detection and uses less reagents, thus resulting in appreciable cost savings.

scholarly journals Engineering super mycovirus donor strains of chestnut blight fungus by systematic disruption of multilocusvicgenes

2016 ◽  
Vol 113 (8) ◽  
pp. 2062-2067 ◽  
Author(s):  
Dong-Xiu Zhang ◽  
Donald L. Nuss
Keyword(s):  
Virus Transmission ◽  
Pathogenic Fungi ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Marker Genes ◽  
Chestnut Blight Fungus ◽  
Selectable Marker Genes ◽  
Recombination System ◽  
Biological Control Potential ◽  
Classical Genetics

Transmission of mycoviruses that attenuate virulence (hypovirulence) of pathogenic fungi is restricted by allorecognition systems operating in their fungal hosts. We report the use of systematic molecular gene disruption and classical genetics for engineering fungal hosts with superior virus transmission capabilities. Four of five diallelic virus-restricting allorecognition [vegetative incompatibility (vic)] loci were disrupted in the chestnut blight fungusCryphonectria parasiticausing an adapted Cre-loxPrecombination system that allowed excision and recycling of selectable marker genes (SMGs). SMG-free, quadruplevicmutant strains representing both allelic backgrounds of the remainingviclocus were then produced through mating. In combination, these super donor strains were able to transmit hypoviruses to strains that were heteroallelic at one or all of the virus-restrictingvicloci. These results demonstrate the feasibility of modulating allorecognition to engineer pathogenic fungi for more efficient transmission of virulence-attenuating mycoviruses and enhanced biological control potential.

scholarly journals 75 years of the chestnut blight fungus Cryphonectria parasitica (Murr.) Barr in Europe

2014 ◽  
pp. 82-85
Author(s):  
László Radócz ◽  
Gábor Görcsös ◽  
Gábor Tarcali ◽  
Gabriella Kovács ◽  
Qin Ling
Keyword(s):  
Biological Control ◽  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
European Chestnut ◽  
High Prevalence ◽  
History Of ◽  
Short Time ◽  
High Diversity

The chestnut blight fungus Cryphonectria parasitica is a native pathogen in East Asia and has been introduced into North America and Europe. Historical records and population genetic studies revealed at least three major introduction events from Asia into Europe. Nowadays, chestnut blight is present in almost the entire distribution range of European chestnut, i.e. from the Iberian Peninsula to the Caucasus. The C. parasitica population in most countries has been studied in respect to the diversity of vegetative compatibility (vc) types and the occurrence of hypovirulence. The vc type diversity of the different populations varied considerably. Typically, a high diversity of vc types has been found in areas with a long history of chestnut blight and where sexual recombination between divergent genotypes commonly has occurred. On the other hand, newly established populations often showed a low diversity with only one, or a few vc types present. Hypovirulence, i.e. the occurrence of C. parasitica isolates infected by Cryphonectria hypovirus 1 has been found widespread in Europe. Natural dissemination and active biological control applications have lead to a high prevalence of the hypovirus and to the recovery of many chestnut stands. Virulent cankers became hypovirus-infected within a short time and ceased expansion. There is concern that the diversity of vegetative compatibility types could increase in Europe through sexual reproduction between C. parasitica genotypes originating from different introductions. A higher level of vegetative incompatibility would not only hamper hypovirus spread within a population but could also select for lower virulence in CHV-1 and subsequently lead to an erosion of biological control. Recent studies, however, indicate that the vc type barriers are not so restrictive than previously assumed and that so far no evidence for an erosion of biological control system in high diversity populations can be observed.

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 Characterization of a Hypovirus-Regulated Septin Cdc11 Ortholog, CpSep1, from the Chestnut Blight Fungus Cryphonectria parasitica

2019 ◽  
Vol 32 (3) ◽  
pp. 286-295 ◽  
Author(s):  
Myeongjin Jo ◽  
Kum-Kang So ◽  
Yo-Han Ko ◽  
Jeesun Chun ◽  
Jung-Mi Kim ◽  
...  
Keyword(s):  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Null Mutant ◽  
Wild Type ◽  
Chestnut Blight Fungus ◽  
Germination Process ◽  
Cryphonectria Hypovirus ◽  
Null Mutants

We identified a protein spot showing downregulation in the presence of Cryphonectria hypovirus 1 and tannic acid supplementation as a septin subunit with the highest homology to the Aspergillus nidulans aspA gene, an ortholog of the Saccharomyces cerevisiae Cdc11 gene. To analyze the functional role of this septin component (CpSep1), we constructed its null mutant and obtained a total of eight CpSep1-null mutants from 137 transformants. All CpSep1-null mutants showed retarded growth, with fewer aerial mycelia and intense pigmentation on plates of potato dextrose agar supplemented with L-methionine and biotin. When the marginal hyphae were examined, hyperbranching was observed in contrast to the wild type. The inhibition of colonial growth was partially recovered when the CpSep1-null mutants were cultured in the presence of the osmostabilizing sorbitol. Conidia production of the CpSep1-null mutants was significantly increased by at least 10-fold more. Interestingly, the conidial morphology of the CpSep1-null mutants changed to circular in contrast to the typical rod-shaped spores of the wild type, indicating a role of septin in the spore morphology of Cryphonectria parasitica. However, no differences in the germination process were observed. Virulence assays using excised chestnut bark, stromal pustule formation on chestnut stems, and apple inoculation indicated that the CpSep1 gene is important in pathogenicity.

scholarly journals Differential Transfer and Dissemination of Hypovirus and Nuclear and Mitochondrial Genomes of a Hypovirus-Infected Cryphonectria parasitica Strain after Introduction into a Natural Population

2003 ◽  
Vol 69 (7) ◽  
pp. 3767-3771 ◽  
Author(s):  
Patrik J. Hoegger ◽  
Ursula Heiniger ◽  
Ottmar Holdenrieder ◽  
Daniel Rigling
Keyword(s):  
Biological Control ◽  
Mitochondrial Dna ◽  
Nuclear Genome ◽  
Cryphonectria Parasitica ◽  
Plant Diseases ◽  
Mitochondrial Genomes ◽  
Chestnut Blight ◽  
Fungal Host ◽  
Chestnut Blight Fungus ◽  
Living Organisms

ABSTRACT Biological control of plant diseases generally requires release of living organisms into the environment. Cryphonectria hypoviruses function as biological control agents for the chestnut blight fungus, Cryphonectria parasitica, and hypovirus-infected C. parasitica strains can be used to treat infected trees. We used naturally occurring molecular marker polymorphisms to examine the persistence and dissemination of the three genomes of a hypovirus-infected C. parasitica strain, namely, the double-stranded RNA genome of Cryphonectria hypovirus 1 (CHV1) and the nuclear and mitochondrial genomes of its fungal host. The hypovirus-infected strain was experimentally introduced into a blight-infested chestnut coppice forest by treating 73 of 246 chestnut blight cankers. Two years after introduction, the hypovirus had disseminated to 36% of the untreated cankers and to 35% of the newly established cankers. Spread of the hypovirus was more frequent within treated sprout clusters than between sprout clusters. Mitochondrial DNA of the introduced fungus also was transferred into the resident C. parasitica population. Concomitant transfer of both the introduced hypovirus and mitochondrial DNA was detected in almost one-half of the treated cankers analyzed. The introduced mitochondrial DNA haplotype also was found in three resident isolates from newly established cankers. The nuclear genome of the introduced strain persisted in the treated cankers but did not spread beyond them.

scholarly journals Genetic Control of Horizontal Virus Transmission in the Chestnut Blight Fungus, Cryphonectria parasitica

Genetics ◽  
2001 ◽  
Vol 159 (1) ◽  
pp. 107-118 ◽  
Author(s):  
Paolo Cortesi ◽  
Charles E McCulloch ◽  
Haiyue Song ◽  
Haiqun Lin ◽  
Michael G Milgroom
Keyword(s):  
Logistic Regression ◽  
Regression Model ◽  
Logistic Regression Model ◽  
Horizontal Transmission ◽  
Natural Populations ◽  
Virus Transmission ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Vegetative Incompatibility ◽  
Chestnut Blight Fungus

Abstract Vegetative incompatibility in fungi has long been known to reduce the transmission of viruses between individuals, but the barrier to transmission is incomplete. In replicated laboratory assays, we showed conclusively that the transmission of viruses between individuals of the chestnut blight fungus Cryphonectria parasitica is controlled primarily by vegetative incompatibility (vic) genes. By replicating vic genotypes in independent fungal isolates, we quantified the effect of heteroallelism at each of six vic loci on virus transmission. Transmission occurs with 100% frequency when donor and recipient isolates have the same vic genotypes, but heteroallelism at one or more vic loci generally reduces virus transmission. Transmission was variable among single heteroallelic loci. At the extremes, heteroallelism at vic4 had no effect on virus transmission, but transmission occurred in only 21% of pairings that were heteroallelic at vic2. Intermediate frequencies of transmission were observed when vic3 and vic6 were heteroallelic (76 and 32%, respectively). When vic1, vic2, and vic7 were heteroallelic, the frequency of transmission depended on which alleles were present in the donor and the recipient. The effect of heteroallelism at two vic loci was mostly additive, although small but statistically significant interactions (epistasis) were observed in four pairs of vic loci. A logistic regression model was developed to predict the probability of virus transmission between vic genotypes. Heteroallelism at vic loci, asymmetry, and epistasis were the dominant factors controlling transmission, but host genetic background also was statistically significant, indicating that vic genes alone cannot explain all the variation in virus transmission. Predictions from the logistic regression model were highly correlated to independent transmission tests with field isolates. Our model can be used to estimate horizontal transmission rates as a function of host genetics in natural populations of C. parasitica.

scholarly journals Genetics of Vegetative Incompatibility inCryphonectria parasitica

1998 ◽  
Vol 64 (8) ◽  
pp. 2988-2994 ◽  
Author(s):  
Paolo Cortesi ◽  
Michael G. Milgroom
Keyword(s):  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Virus Transmission ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Vegetative Incompatibility ◽  
Genetic Studies ◽  
Future Studies ◽  
Chestnut Blight Fungus

ABSTRACT Vegetative incompatibility in the chestnut blight fungus,Cryphonectria parasitica, in Europe is controlled by six unlinked vic loci, each with two alleles. Four previously identified vic loci (vic1, vic2,vic3, and vic4) were polymorphic in European vegetative compatibility (vc) types. Two new loci, vic6 andvic7, also were identified among European vc types. In one cross, vic genes segregated independently at five loci, and 194 progeny were assigned to 32 vc types; none of these loci were linked. A total of 64 vc types were identified from all crosses. All 64 genotypes possible from six vic loci, each with two alleles (26 = 64), were identified and assigned to vc types. Based on our model, vc types v-c 5 and v-c 10, which had been used in previous genetic studies, differ by only five vic genes. Future studies of vc types in C. parasitica can use knowledge of vic genotypes for analysis of population genetic structure based on vic allele frequencies and to determine the effect of each vic gene on virus transmission between vc types.

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