scholarly journals Temporal and spatial genetic population structure of Cryphonectria parasitica and its associated hypovirus across an invasive range of chestnut blight in Europe

2021 ◽  
Author(s):  
Marin Ježić ◽  
Janine Melanie Schwarz ◽  
Simone Prospero ◽  
Kiril Sotirovski ◽  
Mihajlo Risteski ◽  
...  
Keyword(s):  
Population Structure ◽  
Cryphonectria Parasitica ◽  
Population Diversity ◽  
Chestnut Blight ◽  
Genetic Population ◽  
Invasive Range ◽  
Temporal And Spatial ◽  
Cryphonectria Hypovirus ◽  
High Diversity ◽  
Over Time

Chestnut blight has spread throughout Europe since the introduction of its causal agent Cryphonectria parasitica over 70 years ago. In our study, we have analysed diversity of vegetative compatibility (vc) and microsatellite genotypes of C. parasitica, as well as sequence diversity of Cryphonectria hypovirus 1 (CHV1) in six populations from Switzerland, Croatia and North Macedonia. Resampling of local populations that were already investigated more than a decade ago allowed us to analyse the spatial and temporal population structure across an invasive range of the pathogen in Europe. Regardless which genetic marker was used, the over 60 year-old Swiss and Croatian populations had a high population diversity, while more recent North Macedonian populations were mostly clonal. These diversity differences between the investigated populations remained stable over time. A high diversity of CHV1 was observed in all three countries, with North Macedonian strains forming a separate cluster from strains obtained in other countries. No correlation between vc diversity and CHV1 prevalence was observed, suggesting a well-established and maintained natural hypovirulence in all countries, further corroborated by an observed increase in genetic diversity of Croatian C. parasitica populations over time, without collapse of CHV1 prevalence.

scholarly journals Hypovirus Virulence and Vegetative Incompatibility in Populations of the Chestnut Blight Fungus

2012 ◽  
Vol 102 (12) ◽  
pp. 1161-1167 ◽  
Author(s):  
Sarah Franziska Bryner ◽  
Daniel Rigling
Keyword(s):  
Biocontrol Agent ◽  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Chestnut Blight ◽  
Vegetative Incompatibility ◽  
Tree Disease ◽  
Chestnut Blight Fungus ◽  
Fungal Populations ◽  
Cryphonectria Hypovirus ◽  
High Diversity

Cryphonectria hypovirus 1 hyperparasitizes the chestnut blight fungus Cryphonectria parasitica and acts as a biocontrol agent for this serious tree disease. The virus is transmitted cytoplasmatically between fungal individuals. However, highly virulent viruses strongly debilitate their host and, thus, reduce their own transmission probability. Furthermore, vegetative incompatibility between fungi is an important transmission barrier. Therefore, virulent viruses are expected to be strongly selected against in fungal populations with high levels of vegetative incompatibility, eventually leading to the erosion of biocontrol. To test this prediction, we assessed the virulence of the virus in four European C. parasitica populations with high diversity of vegetative compatibility types and in four populations with low diversity. We expected the degree of virus virulence to be lower in fungal populations with high levels of vegetative incompatibility. However, our results did not reveal such a trend. No significant differences in virus virulence between populations with low versus high diversity of vegetative compatibility types were observed. There was no evidence for an erosion of disease control due to the presence of these transmission barriers. Thus, the findings of this study are promising for the sustainability of Cryphonectria hypovirus 1 as a biocontrol agent for chestnut blight in Europe.

scholarly journals Dynamics of Cryphonectria hypovirus Infection in Chestnut Blight Cankers

2014 ◽  
Vol 104 (9) ◽  
pp. 918-925 ◽  
Author(s):  
Sarah Franziska Bryner ◽  
Simone Prospero ◽  
Daniel Rigling
Keyword(s):  
Virus Infection ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Seedling Mortality ◽  
Chestnut Blight Fungus ◽  
European Chestnut ◽  
Virulent Strains ◽  
Coppice Forest ◽  
Cryphonectria Hypovirus ◽  
Over Time

Virulent strains of the chestnut blight fungus Cryphonectria parasitica cause lethal bark cankers on chestnut trees. Infection of C. parasitica with Cryphonectria hypovirus 1 in Europe biologically controls this disease, leading to nonlethal and inactive cankers. Unexpectedly, virus-free C. parasitica strains have been isolated from inactive cankers. In this study, we compared the virulence of virus-infected and virus-free C. parasitica strains isolated from either inactive or active cankers on chestnut seedlings and sprouts. In the seedling experiment, we assessed canker growth and seedling mortality. In the sprout experiment, we also assessed canker growth and made fungal reisolations to determine virus infection and immigration of foreign vegetative compatibility (vc) types over a period of 13 years in a coppice forest. Overall, the virulence of virus-free C. parasitica strains isolated from inactive versus active cankers did not differ. Significant differences were only attributed to virus infection. Virus infection and fungal strain composition in cankers changed over time. Foreign vc types immigrated into cankers and virus-free cankers became virus-infected within a few years. Most of the cankers were callused over time and became inactive. However, we observed that the virus did not always persist in these cankers. This study demonstrates that virus spread occurs effectively in European chestnut forests and that this biocontrol system is highly dynamic.

scholarly journals Hyperparasites Influence Population Structure of the Chestnut Blight Pathogen, Cryphonectria parasitica

2013 ◽  
Vol 103 (12) ◽  
pp. 1280-1286 ◽  
Author(s):  
Joshua C. Springer ◽  
Anita L. Davelos Baines ◽  
Dennis W. Fulbright ◽  
Matthew T. Chansler ◽  
Andrew M. Jarosz
Keyword(s):  
Population Structure ◽  
North America ◽  
Asexual Reproduction ◽  
Population Level ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
History Of ◽  
Fungal Populations ◽  
Pathogen Populations

Vegetative compatibility (VC) is commonly used to characterize structure and diversity in fungal populations. In the chestnut blight fungus, Cryphonectria parasitica, high VC diversity is hypothesized to be responsible for the failure of hyperparasitic mycoviruses to spread through pathogen populations in North America. To test this hypothesis, we assessed VC diversity at three recovering sites in Michigan where mycoviruses had invaded and compared them with four epidemic population sites where mycoviruses were absent. VC diversity was assessed for samples collected in 1996 and 2009, which allowed us to determine how C. parasitica populations changed with time. Twelve VC types were found in 1996 while 29 were found in 2009; 75% of types overlapped between the sample dates. Sites where mycoviruses were present had unique VC structures with the exception of the recovering population site at County Line where the main VC group was also detected at two epidemic sites. With one exception, epidemic sites contained more VC groups and displayed higher population level diversity than recovering sites. Mating-type analyses of blight populations revealed that two of three recovering populations were significantly skewed for MAT2 suggesting asexual reproduction, while epidemic sites with a long history of blight infection had ratios near 50:50 suggesting sexual reproduction. We propose that selection in the largely asexual C. parasitica populations at two recovering sites favors the most-fit fungal genotype by mycovirus combination and results in reduced diversity relative to the sexually reproducing pathogen populations at epidemic sites.

Intercontinental Population Structure of the Chestnut Blight Fungus, Cryphonectria parasitica

Mycologia ◽  
1996 ◽  
Vol 88 (2) ◽  
pp. 179 ◽  
Author(s):  
Michael G. Milgroom ◽  
Kerong Wang ◽  
Yang Zhou ◽  
Susanne E. Lipari ◽  
Shigeru Kaneko
Keyword(s):  
Population Structure ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus

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 Hail-Induced Infections of the Chestnut Blight Pathogen Cryphonectria parasitica Depend on Wound Size and May Lead to Severe Diebacks

2020 ◽  
Vol 110 (7) ◽  
pp. 1280-1293
Author(s):  
Guglielmo Lione ◽  
Luana Giordano ◽  
Massimo Turina ◽  
Paolo Gonthier
Keyword(s):  
Logistic Model ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Risk Of Infection ◽  
North West ◽  
The North ◽  
Single Location ◽  
Entry Points ◽  
Cryphonectria Hypovirus

This study combined phytosanitary surveys, laboratory analyses, and mathematical modeling to show how hail-induced wounds can foster the infections of the blight pathogen Cryphonectria parasitica, locally associated with extensive dieback of chestnut (Castanea sativa). Orchards and coppices located within and outside the assessed dieback area in a single location in the North West of Italy were inspected to appraise the abundance of hail-induced wounds and C. parasitica infections. The incidence of C. parasitica was significantly higher within the dieback area compared with outside (92% versus 60%; P < 0.05). Hail-induced wounds were observed on small branches and shoots of all trees sampled within the dieback area, whereas they were less abundant outside (20% of trees), suggesting either that the dieback was directly associated with the injuries caused by the hailstorms or that those injuries may have facilitated infections of C. parasitica. Isolations conducted on 359 branches and shoots showed that hail-induced wounds served as infection courts for C. parasitica and that infections depended on the size rather than on the number of hail wounds. We fitted a logistic model showing that hail-induced wounds whose perimeter was larger than 66 mm were at particular risk of C. parasitica infection. A newly designed geometrical-based model is proposed to relate hailstones size, hail wound perimeter, and the risk of infection. We established that hail-induced wounds are entry points for virulent and hypovirulent strains of C. parasitica, since 6.5% of isolates were infected by Cryphonectria hypovirus-1.

scholarly journals The development of population structure of Cryphonectria parasitica on European chestnut (Castanea sativa Mill.) in the Experimental Castanetarium Horné Lefantovce, observed over a 12-year study period

2009 ◽  
Vol 36 (No. 2) ◽  
pp. 55-60 ◽  
Author(s):  
K. Adamčíková ◽  
M. Kobza ◽  
G. Juhásová
Keyword(s):  
Population Structure ◽  
Castanea Sativa ◽  
Morphological Characters ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Experimental Plot ◽  
Disease Symptoms ◽  
European Chestnut ◽  
Blight Disease ◽  
First Time

: We studied occurrence of chestnut blight disease in the Experimental Castanetarium Horné Lefantovce, SW Slovakia. The study ran in years 2006–2007 on a set consisting of 889 chestnut trees growing in the clonal orchard on Biological Plot 105. From this number, 857 trees were found healthy without disease symptoms. The chestnut blight disease was identified on 32 of them. The infected trees were examined for presence of pycnidia and perithecia of the causal agent. In all positive cases, the observed morphological characters indicated virulency of the obtained isolates. No hypovirulent isolate was detected on the evaluated experimental plot. In total, six vegetative compatibility (vc) types were specified in the sample consisting of 31 isolates. Our vc types corresponded to the European vc types EU 2, EU 12, EU 13, EU 14, EU 17, EU 19. Two vc types – EU 2 and EU 19 – were dominant. Vc type EU 19 accounted 35.5% and EU 2 32.2% of isolates. The vc type EU 19, which was the most frequent one in the evaluated site, was detected in Slovakia for the first time.

scholarly journals DNA fingerprinting and analysis of population structure in the chestnut blight fungus, Cryphonectria parasitica.

Genetics ◽  
1992 ◽  
Vol 131 (2) ◽  
pp. 297-306 ◽  
Author(s):  
M G Milgroom ◽  
S E Lipari ◽  
W A Powell
Keyword(s):  
Population Structure ◽  
Null Hypothesis ◽  
Random Mating ◽  
Population Sample ◽  
Cryphonectria Parasitica ◽  
The Other ◽  
Chestnut Blight ◽  
Dna Fingerprints ◽  
Restriction Fragments ◽  
Chestnut Blight Fungus

Abstract We analyzed DNA fingerprints in the chestnut blight fungus, Cryphonectria parasitica, for stability, inheritance, linkage and variability in a natural population. DNA fingerprints resulting from hybridization with a dispersed moderately repetitive DNA sequence of C. parasitica in plasmid pMS5.1 hybridized to 6-17 restriction fragments per individual isolate. In a laboratory cross and from progeny from a single perithecium collected from a field population, the presence/absence of 11 fragments in the laboratory cross and 12 fragments in the field progeny set segregated in 1:1 ratios. Two fragments in each progeny set cosegregated; no other linkage was detected among the segregating fragments. Mutations, identified by missing bands, were detected for only one fragment in which 4 of 43 progeny lacked a band present in both parents; no novel fragments were detected in any progeny. All other fragments appeared to be stably inherited. Hybridization patterns did not change during vegetative growth or sporulation. However, fingerprint patterns of single conidial isolates of strains EP155 and EP67 were found to be heterogenous due to mutations that occurred during culturing in the laboratory since these strains were first isolated in 1976-1977. In a population sample of 39 C. parasitica isolates, we found 33 different fingerprint patterns with pMS5.1. Most isolates differed from all other isolates by the presence or absence of several fragments. Six fingerprint patterns each occurred twice. Isolates with identical fingerprints occurred in cankers on the same chestnut stems three times; isolates within the other three pairs were isolated from cankers more than 5 m apart. The null hypothesis of random mating in this population could not be rejected if the six putative clones were removed from the analysis. Thus, a rough estimate of the clonal fraction of this population is 6 in 39 isolates (15.4%).

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