Genetic diversification of the chestnut blight fungus Cryphonectria parasitica and its associated hypovirus in Germany

Peters, Franziska S.; Bußkamp, Johanna; Prospero, Simone; Rigling, Daniel; Metzler, B.

doi:10.1016/j.funbio.2013.11.009

Cited by 34 publications

(32 citation statements)

References 72 publications

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“…The other subtypes, especially F1, are usually less abundant because the increased aggressiveness of the virus causes significant reduction in fungal growth and therefore makes infected individuals less likely to persist. F1 and other subtypes have been found in some parts of France, Spain, eastern Turkey and Germany . The CHV‐1 virus does not occur naturally in USA but is present in a few locations such as in Virginia where it has been released for the biological control of American chestnut blight, Wisconsin or Maryland .…”

Section: Discussionmentioning

confidence: 99%

Hypovirulent effect of theCryphonectria hypovirus 1in British isolates ofCryphonectria parasitica

Romon-Ochoa

Gorton

Lewis

et al. 2019

Pest Management Science

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Background Chestnut blight, caused by Cryphonectria parasitica, is controlled in many European countries by the naturally occurring mycovirus Cryphonectria hypovirus 1 (CHV‐1). During surveys of recently identified chestnut blight outbreak in England, CHV‐1 was detected in several individuals of the pathogen isolated from affected trees. We investigated two of these CHV‐1‐infected isolates (L‐6 and Db‐1) as potential biocontrol agents for deployment in the UK comparing their virulence against virus‐free (M1275) and hypovirulent (M784) European isolates by inoculating sweet chestnut seedlings. Results Both the European CHV‐1 M784 hypovirulent isolate and UK L‐6 isolate formed significantly smaller lesions in sweet chestnut seedling bark than the other three isolates (Db‐1, and virulent isolates FTC121 and M1275). The highest virus concentration was detected in isolate M784, followed by L‐6, with the lowest concentration in isolate Db‐1. White colony colouration indicative of hypovirulence was common in colonies re‐isolated from smaller lesions, and the same isolates also tended to be slower growing in culture, have a higher virus concentration, and caused less epicormic growth and fewer stromata to be present in plants. L‐6 and Db‐1 virus sequences, respectively, matched the virus haplotype E‐5 detected previously in Switzerland and a mutation of the same subtype I haplotype. Conclusion Isolate L‐6 could potentially act as biocontrol for chestnut blight outbreaks in the UK but further laboratory and field experiments are needed. © 2019 Crown copyright. Pest Management Science © 2019 Society of Chemical Industry

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Section: Discussionmentioning

confidence: 99%

Hypovirulent effect of theCryphonectria hypovirus 1in British isolates ofCryphonectria parasitica

Romon-Ochoa

Gorton

Lewis

et al. 2019

Pest Management Science

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“…Although the currently defined six diallelic vic loci account for the vic diversity of C. parasitica populations in the forest setting in the eastern United States (36), it is clear that additional vic diversity is present in Europe (19,20,37) and Asia (38). It is envisioned that the comparative genomic approach (22,23) for identifying the currently defined vic loci could be used to identify additional C. parasitica vic alleles of existing vic loci or entirely new vic loci.…”

Section: Discussionmentioning

confidence: 99%

Engineering super mycovirus donor strains of chestnut blight fungus by systematic disruption of multilocus vic genes

Zhang

Nuss

2016

Proc. Natl. Acad. Sci. U.S.A.

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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 fungus Cryphonectria parasitica using an adapted Cre-loxP recombination system that allowed excision and recycling of selectable marker genes (SMGs). SMG-free, quadruple vic mutant strains representing both allelic backgrounds of the remaining vic locus 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-restricting vic loci. 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.M ycovirus infections have been reported to reduce virulence (hypovirulence) for a wide range of plant pathogenic fungi, providing potential for biological disease control (1-6). For hypovirulence to be effective, the virulence-attenuating viruses must be efficiently transmitted from infected hypovirulent strains to uninfected virulent strains (5, 7). Mycoviruses generally have evolved exclusive intracellular lifestyles (8). With very few exceptions (9), mycovirus infections cannot be initiated by exposure of uninfected hyphae to cell extracts or secretions from infected fungal isolates. Transmission is limited to intracellular mechanisms, vertical transmission through asexual spores, and horizontal transmission through anastomosis (fusion of hyphae).Horizontal mycovirus transmission to uninfected isolates of the same fungal species is complicated by nonself allorecognition genetic systems, termed "heterokaryon" or "vegetative incompatibility" (vic), which operate widely in filamentous fungi (10). Interactions between genetically distinct individuals of the same species result in an incompatible reaction that triggers localized programmed cell death (PCD), forming a line of demarcation, or barrage, along the zone of contact (10-12) and restricting cytoplasmic transmission of viruses and other cytoplasmic elements (1,(13)(14)(15).A negative correlation between vic diversity and virus transmission has been reported for several fungal hosts (1, 16), but has most extensively been demonstrated for the chestnut blight fungus Cryphonectria parasitica infected with virulence-attenuating hypoviruses (7,(17)(18)(19)(20). Genetic analyses have defined six diallelic vic genetic loci for C. parasitica (21). These loci and associated genes were recently identified at the molecular level through a comparative genomics approach (22, 23) ( Table 1). Independent gene disruption analysis of 12 genes associated with these loci (22, 23) ...

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“…parasitica population structure has been assessed using several molecular markers, including restriction fragment length polymorphisms (RFLPs) (21,22), sequence-characterized amplified regions (SCARs) (23,24), microsatellites (simple sequence repeats, or SSRs) (4,25,26), and partial (4-locus) vic genotypes (27). Molecular tools for rapid and precise determination of vic genotypic diversity would be useful not only for population structure analysis but also for predicting and evaluating the impact of hypovirus release on blight control (18).…”

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confidence: 99%

Multilocus PCR Assays Elucidate Vegetative Incompatibility Gene Profiles of Cryphonectria parasitica in the United States

Short

Double

Nuss

et al. 2015

Appl Environ Microbiol

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Chestnut blight is a devastating disease of Castanea spp. Mycoviruses that reduce virulence (hypovirulence) of the causative agent, Cryphonectria parasitica, can be used to manage chestnut blight. However, vegetative incompatibility (vic) barriers that restrict anastomosis-mediated virus transmission hamper hypovirulence efficacy. In order to effectively determine the vegetative incompatibility genetic structure of C. parasitica field populations, we have designed PCR primer sets that selectively amplify and distinguish alleles for each of the six known diallelic C. parasitica vic genetic loci. PCR assay results were validated using a panel of 64 European tester strains with genetically determined vic genotypes. Analysis of 116 C. parasitica isolates collected from five locations in the eastern United States revealed 39 unique vic genotypes and generally good agreement between PCR and tester strain coculturing assays in terms of vic diversity and genotyping. However, incongruences were observed for isolates from multiple locations and suggested that the coculturing assay can overestimate diversity at the six known vic loci. The availability of molecular tools for rapid and precise vic genotyping significantly improves the ability to predict and evaluate the efficacy of hypovirulence and related management strategies.

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Genetic diversification of the chestnut blight fungus Cryphonectria parasitica and its associated hypovirus in Germany

Cited by 34 publications

References 72 publications

Hypovirulent effect of theCryphonectria hypovirus 1in British isolates ofCryphonectria parasitica

Hypovirulent effect of theCryphonectria hypovirus 1in British isolates ofCryphonectria parasitica

Engineering super mycovirus donor strains of chestnut blight fungus by systematic disruption of multilocus vic genes

Multilocus PCR Assays Elucidate Vegetative Incompatibility Gene Profiles of Cryphonectria parasitica in the United States

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