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.

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 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 Population genetic structure in European populations of Spiranthes romanzoffiana set in the context of other genetic studies on orchids

Heredity ◽  
2003 ◽  
Vol 92 (3) ◽  
pp. 218-227 ◽  
Author(s):  
A D Forrest ◽  
M L Hollingsworth ◽  
P M Hollingsworth ◽  
C Sydes ◽  
R M Bateman
Keyword(s):  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Genetic Studies ◽  
European Populations

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

2015 ◽  
Vol 81 (17) ◽  
pp. 5736-5742 ◽  
Author(s):  
Dylan P. G. Short ◽  
Mark Double ◽  
Donald L. Nuss ◽  
Cameron M. Stauder ◽  
William MacDonald ◽  
...  
Keyword(s):  
United States ◽  
Management Strategies ◽  
Virus Transmission ◽  
The United States ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Eastern United States ◽  
Vegetative Incompatibility ◽  
Content Type ◽  
Primer Sets

ABSTRACTChestnut blight is a devastating disease ofCastaneaspp. 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 ofC. parasiticafield populations, we have designed PCR primer sets that selectively amplify and distinguish alleles for each of the six known diallelicC. parasiticavicgenetic loci. PCR assay results were validated using a panel of 64 European tester strains with genetically determinedvicgenotypes. Analysis of 116C. parasiticaisolates collected from five locations in the eastern United States revealed 39 uniquevicgenotypes and generally good agreement between PCR and tester strain coculturing assays in terms ofvicdiversity and genotyping. However, incongruences were observed for isolates from multiple locations and suggested that the coculturing assay can overestimate diversity at the six knownvicloci. The availability of molecular tools for rapid and precisevicgenotyping significantly improves the ability to predict and evaluate the efficacy of hypovirulence and related management strategies.

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.

Sign in / Sign up

Export Citation Format

Share Document