scholarly journals Chestnut blight fungus in Croatia: diversity of vegetative compatibility types, mating types and genetic variability of associatedCryphonectria hypovirus 1

2008 ◽  
Vol 57 (6) ◽  
pp. 1086-1096 ◽  
Author(s):  
L. Krstin ◽  
S. Novak-Agbaba ◽  
D. Rigling ◽  
M. Krajačić ◽  
M. Ćurković Perica
Keyword(s):  
Genetic Variability ◽  
Vegetative Compatibility ◽  
Chestnut Blight ◽  
Mating Types ◽  
Chestnut Blight Fungus

Population biology of the chestnut blight fungus, Cryphonectria parasitica

1995 ◽  
Vol 73 (S1) ◽  
pp. 311-319 ◽  
Author(s):  
Michael G. Milgroom
Keyword(s):  
Gene Flow ◽  
North America ◽  
Population Biology ◽  
Random Mating ◽  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Chestnut Blight ◽  
Vegetative Compatibility Groups ◽  
Chestnut Blight Fungus ◽  
Endothia Parasitica

Interest in the population biology of the chestnut blight fungus Cryphonectria parasitica has been motivated largely by the potential for biological control of chestnut blight with fungal viruses that cause hypovirulence. Earlier studies gave valuable insights into the correlation between diversity of vegetative compatibility groups and transmission of hypovirulence viruses. However, inferences about evolutionary processes affecting populations were not possible because vegetative compatibility groups are not genetically defined. Using restriction fragment length polymorphism markers, however, progress has been made in studying the origin of C. parasitica in North America, gene flow among populations, dispersal within populations, and recombination and the mating system. Cryphonectria parasitica populations in North America are genetically more similar to populations in Japan than in China, which is consistent with previous speculations that this fungus was introduced from Japan. Populations in China and Japan are quite different, suggesting little or no gene flow between these areas. Restricted gene flow and genetic drift are probably the dominant evolutionary forces shaping North American populations, with approximately 20% of gene diversity due to differences among populations (GST = 0.20). Two populations of C. parasitica in Michigan and one population in Italy are primarily clonal in structure. In contrast, sexual reproduction appears to be common in populations in eastern North America, although most of these populations deviate significantly from random mating. Deviations from random mating are most likely due to self-fertilization (uniparental inbreeding), restricted dispersal of male gametes, and mating between individuals that are more closely related genetically than would be expected by chance (biparental inbreeding). Aggregations of similar genotypes in space suggest that populations of C. parasitica may be structured into genetic neighborhoods by restricted dispersal. Future research efforts in this system will explore isolation by distance and address questions of hypovirulence virus coevolution with its fungal host. Key words: Cryphonectria parasitica, Endothia parasitica, chestnut blight, genetic neighbourhoods, inbreeding.

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 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 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.

Spatial pattern analysis of vegetative compatibility groups in the chestnut blight fungus, Cryphonectria parasitica

1991 ◽  
Vol 69 (7) ◽  
pp. 1407-1413 ◽  
Author(s):  
Michael G. Milgroom ◽  
William L. MacDonald ◽  
Mark L. Double
Keyword(s):  
Average Distance ◽  
Cryphonectria Parasitica ◽  
Mantel Test ◽  
Vegetative Compatibility ◽  
Chestnut Blight ◽  
Spatial Pattern Analysis ◽  
Vegetative Compatibility Groups ◽  
Clear Cut ◽  
Chestnut Blight Fungus ◽  
Endothia Parasitica

Vegetative compatibility groups were determined for 914 isolates of the chestnut blight fungus, Cryphonectria (Endothia) parasitica, collected over a 5-year period from American chestnut trees in eight regenerating clear-cut plots. We tested the hypothesis that the average distance between individuals in the same vegetative compatibility group is not different from the average distance between individuals with vegetative compatibility assigned at random. Nonrandom patterns were detected in all plots at least once during the study, indicating that vegetative compatibility groups were often aggregated. However, when multiple occurrences of vegetative compatibility groups on the same tree were eliminated from the analysis, there was only one test (out of 98 in total) in which the null hypothesis was rejected. We conclude that nonrandom patterns of vegetative compatibility groups are due primarily to multiple occurrences of vegetative compatibility groups on the same trees. Nearly half of all new cankers detected once the epidemic got started were in the same vegetative compatibility groups as cankers previously resident on the same tree. These data are consistent with the hypothesis that populations of C. parasitica are partly clonal in structure. Key words: Endothia parasitica, hypovirulence, Mantel test, matrix comparison, spatial autocorrelation.

scholarly journals Effect of the media on morphology of Cryphonectria parasitica (Murr.) Barr isolates and their Vegetative Compatibility Groups

2015 ◽  
pp. 38-42
Author(s):  
Gabriella Kovács ◽  
László Radócz
Keyword(s):  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Bark Extract ◽  
Chestnut Blight ◽  
Vegetative Compatibility Groups ◽  
Infested Area ◽  
Chestnut Blight Fungus ◽  
Virulent Strains ◽  
Different Types ◽  
The Media

The most dangerous pathogen for the European and American chestnuts is the blight fungus Cryphonectria parasitica (Murrill) Barr. Short after its introduction a big number of chestnut trees were destroyed on the infested area. The control could be really complicated, because of the numerous vegetative compatibility groups of the fungus. There is a type that carries a mycovirus viz. hypovirus in the cytoplasm. We are able to control effectively this pathogen by using mycovirus-carrying strains (called hypovirulent fungal strains also). In laboratory it is easy to multiply the virulent and the hypovirulent strains of the fungus but do not easy to differentiate colonies visually on simple PDA medium. During our research, we tested different types of media, based on potato and chestnut bark extract respectively. It was observed that on potato medium the virulent strains produce more orange pigments. So it is more easy to differentiate virulent or hypovirulent isolates of chestnut blight fungus based on colony colour and morphology.

The chestnut blight fungus world tour: successive introduction events from diverse origins in an invasive plant fungal pathogen

2012 ◽  
Vol 21 (16) ◽  
pp. 3931-3946 ◽  
Author(s):  
C. DUTECH ◽  
B. BARRÈS ◽  
J. BRIDIER ◽  
C. ROBIN ◽  
M. G. MILGROOM ◽  
...  
Keyword(s):  
Fungal Pathogen ◽  
Invasive Plant ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
Plant Fungal Pathogen

scholarly journals Genetic Variability of Cercospora coffeicola from Organic and Conventional Coffee Plantings, Characterized by Vegetative Compatibility

2008 ◽  
Vol 98 (11) ◽  
pp. 1205-1211 ◽  
Author(s):  
R. B. Martins ◽  
L. A. Maffia ◽  
E. S. G. Mizubuti
Keyword(s):  
Genetic Variability ◽  
Production Systems ◽  
Diversity Index ◽  
Vegetative Compatibility ◽  
Cercospora Leaf Spot ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Geographical Regions ◽  
Minas Gerais State ◽  
Cercospora Coffeicola

Cercospora leaf spot is a destructive fungal disease that has become a threat to the coffee industry in Brazil. Nevertheless, little is known about populations of its causal agent, Cercospora coffeicola. We evaluated the potential of using nitrogen-nonutilizing (nit) mutants and vegetative compatibility groups (VCGs) to characterize the genetic variability of the C. coffeicola population associated with coffee plantings in Minas Gerais state (MG), Brazil. A total of 90 monosporic isolates were obtained from samples collected according to a hierarchical sampling scheme: (i) state geographical regions (Sul, Mata, and Triângulo), and (ii) production systems (conventional and organic). Nit mutants were obtained and 28 VCGs were identified. The 10 largest VCGs included 72.31% of all isolates, whereas each of the remaining 18 VCGs included 1.54% of the isolates. Isolates of the largest VCGs were found in the three regions sampled. Based on the frequencies of VCGs at each sampled level, we estimated the Shannon diversity index, as well as its richness and evenness components. Genetic variability was high at all hierarchical levels, and a high number of VCGs was found in populations of C. coffeicola associated with both conventional and organic coffee plantings.

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