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Michael G. Milgroom - One of the best experts on this subject based on the ideXlab platform.

  • Fifty-three polymorphic microsatellite loci in the chestnut blight fungus, Cryphonectria parasitica
    Molecular Ecology Notes, 2006
    Co-Authors: Thomas L. Kubisiak, Cyril Dutech, Michael G. Milgroom
    Abstract:

    We report on 53 microsatellite loci for use in population genetic or linkage mapping studies in Cryphonectria parasitica . In 40 isolates collected from throughout the Northern Hemisphere, the number of alleles per locus ranged from two to 14 (mean 5.17) with gene diversity values ranging from 0.049 to 0.859 (mean 0.437). Samples from Asia were more diverse than those from Europe and North America. Most of the markers (48 of 53) were developed from an expressed sequence tag library, and hence, offer the opportunity to examine population structure or provide genome location information for specific expressed genes vs. anonymous genomic regions.

  • Polymorphic sequence-characterized codominant loci in the chestnut blight fungus, Cryphonectria parasitica
    Molecular Ecology Notes, 2005
    Co-Authors: J. E. Davis, Thomas L. Kubisiak, Michael G. Milgroom
    Abstract:

    Studies on the population biology of the chestnut blight fungus, Cryphonectria parasitica, have previously been carried out with dominant restriction fragment length polymorphism (RFLP) fingerprinting markers. In this study, we describe the development of 11 codominant markers from randomly amplified polymorphic DNAs (RAPDs). RAPD fragments were cloned and sequenced, and polymerase chain reaction (PCR) primers were designed flanking insertions/deletions. Primers labelled with fluorescent dyes were combined in multiplex reactions to assay five or six loci simultaneously in a capillary sequencing system. These codominant markers have the potential to complement RFLP methods for studying C. parasitica.

  • mixed mating in natural populations of the chestnut blight fungus Cryphonectria parasitica
    Heredity, 2004
    Co-Authors: Robert E Marra, P Cortesi, M Bissegger, Michael G. Milgroom
    Abstract:

    Mixed mating in natural populations of the chestnut blight fungus, Cryphonectria parasitica

  • mating type heterokaryosis and selfing in Cryphonectria parasitica
    Fungal Genetics and Biology, 2004
    Co-Authors: Cristina I Mcguire, Robert E Marra, Michael G. Milgroom
    Abstract:

    Abstract Selfing in the chestnut blight fungus, Cryphonectria parasitica , occurs by two different genetic mechanisms. Most self-fertile isolates of C. parasitica are heterokaryotic for mating type, and the progeny from selfing segregate for mating type. Further, we resolved mating-type ( MAT ) heterokaryons into homokaryons of both mating types by isolating uninucleate asexual spores (conidia). However, because ascospore progeny, with rare exceptions, are not MAT heterokaryons, C. parasitica must lack a regular mechanism to maintain heterokaryosis by selfing. We hypothesize that heterokaryon formation may occur either because of recurrent biparental inbreeding, or by mating-type switching, possibly one involving some kind of parasexual process. The second mechanism found for selfing in C. parasitica occurred less frequently. Three single-conidial isolates ( MAT-1 and MAT-2 ) selfed and produced progeny that did not segregate for mating type. It is currently not known if meiosis occurs during ascospore formation by this mechanism. Index descriptors: Cryphonectria parasitica , Heterokaryosis, MAT , Mating type, Self-fertility, Self-incompatibility, Self-sterility

  • Low diversity of vegetative compatibility types and mating type of Cryphonectria parasitica in the southern Balkans
    Plant Pathology, 2004
    Co-Authors: Kiril Sotirovski, I. Papazova-anakieva, Niklaus J. Grünwald, Michael G. Milgroom
    Abstract:

    The diversity of vegetative compatibility (vc) types and mating type was estimated in populations of the chestnut blight fungus, Cryphonectria parasitica, throughout Macedonia and from selected areas in Greece. Nearly all of the 786 isolates (94%) from Macedonia were in a single vc type, EU-12; all 379 isolates from Greece were EU-12. Only six of 20 populations in Macedonia had more than one vc type. The diversity of vc types in the most diverse populations of Macedonia was comparable with the least diverse populations found previously in Italy. All but six of the 313 isolates assayed had the same mating type, MAT-1, and no perithecia of Cryphonectria parasitica were observed in any population. These results lead to the conclusion that sexual reproduction does not occur in these populations. The lack of vc type diversity may indicate a high potential for the spread of hypoviruses and successful biological control with transmissible hypovirulence. However, if sexual reproduction should occur in Macedonian populations, up to 32 vc types would be possible by recombination among vegetative incompatibility loci.

Robert E Marra - One of the best experts on this subject based on the ideXlab platform.

  • mixed mating in natural populations of the chestnut blight fungus Cryphonectria parasitica
    Heredity, 2004
    Co-Authors: Robert E Marra, P Cortesi, M Bissegger, Michael G. Milgroom
    Abstract:

    Mixed mating in natural populations of the chestnut blight fungus, Cryphonectria parasitica

  • mating type heterokaryosis and selfing in Cryphonectria parasitica
    Fungal Genetics and Biology, 2004
    Co-Authors: Cristina I Mcguire, Robert E Marra, Michael G. Milgroom
    Abstract:

    Abstract Selfing in the chestnut blight fungus, Cryphonectria parasitica , occurs by two different genetic mechanisms. Most self-fertile isolates of C. parasitica are heterokaryotic for mating type, and the progeny from selfing segregate for mating type. Further, we resolved mating-type ( MAT ) heterokaryons into homokaryons of both mating types by isolating uninucleate asexual spores (conidia). However, because ascospore progeny, with rare exceptions, are not MAT heterokaryons, C. parasitica must lack a regular mechanism to maintain heterokaryosis by selfing. We hypothesize that heterokaryon formation may occur either because of recurrent biparental inbreeding, or by mating-type switching, possibly one involving some kind of parasexual process. The second mechanism found for selfing in C. parasitica occurred less frequently. Three single-conidial isolates ( MAT-1 and MAT-2 ) selfed and produced progeny that did not segregate for mating type. It is currently not known if meiosis occurs during ascospore formation by this mechanism. Index descriptors: Cryphonectria parasitica , Heterokaryosis, MAT , Mating type, Self-fertility, Self-incompatibility, Self-sterility

  • PCR amplification of the mating-type idiomorphs in Cryphonectria parasitica.
    Molecular ecology, 1999
    Co-Authors: Robert E Marra, Michael G. Milgroom
    Abstract:

    In the laboratory, the ascomycete fungus Cryphonectria parasitica is rarely self-fertile, and has a self-incompatibility system that resolves into two intersterility groups, controlled by a single locus. In natural populations, however, self-fertilization occurs frequently. In this report, we show that the C. parasitica self-incompatibility locus (MAT) comprises two idiomorphs (alleles that are highly divergent in sequence), conforming to the paradigm of self-incompatibility as described for other ascomycetes. Starting with a fragment putatively from the MAT-2 idiomorph, we used a PCR-based cloning approach to identify 3.5- and 2-kb sequences unique to MAT-1 and MAT-2 isolates, respectively. These sequences were then used to design idiomorph-specific PCR primer pairs, allowing us to efficiently identify the mating types of isolates, a crucial component of our research on the environmental and genetic factors underlying this mixed mating system.

W.a Powell - One of the best experts on this subject based on the ideXlab platform.

  • Ultraviolet Light-Induced Heterokaryon Formation and Parasexuality in Cryphonectria parasitica
    Experimental Mycology, 1995
    Co-Authors: R Rizwana, W.a Powell
    Abstract:

    Rizwana, R., and Powell, W. A. 1995. Ultraviolet light-induced heterokaryon formation and parasexuality in Cryphonectria parasitica. Experimental Mycology 19, 48-60. The effect of ultraviolet-light on heterokaryon formation, vegetative compatibility, and parasexuality in Cryphonectria parasitica was examined. Heterokaryons of complementary auxotrophic strains could not be made by hyphal anastomosis if the strains belonged to different vegetative compatibility groups. Protoplast fusions overcame incompatibility of strains differing in the alleles of a single but not multiple vegetative incompatibility loci. Fusion of protoplasts from ultraviolet light-treated complementary auxotrophs increased heterokaryon formation by 104 to 105 using the strains differing in alleles of a single vegetative incompatibility gene but had no detectable effect on strains differing in multiple vegetative incompatibility genes. Vegetative compatibility tests of single conidial isolates resolved from these heterokaryons suggest that diploids had formed followed by the loss of one of the VIC alleles. Presence of both auxotrophic markers in some of these single conidial isolates confirms the occurrence of a parasexual cycle. These experiments demonstrate that ultraviolet-light can enhance heterokaryon formation and parasexuality in C. parasitica .

  • Ultraviolet light-induced instability of vegetative compatibility groups of Cryphonectria parasitica
    Phytopathology, 1992
    Co-Authors: R Rizwana, W.a Powell
    Abstract:

    The main objective was to study the effect of ultraviolet (UV) light on vegetative compatibility in the fungus Cryphonectria parasitica. A procedure was developed to detect individual incompatible colonies from cultured lawns of compatible colonies. Incompatibility reactions were observed when protoplasts from two different vegetative compatibility (v-c) groups were mixed and plated on a suitable medium containing red food color (...)

Donald D. Davis - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Cryphonectria parasitica Basal Cankers on Radial Growth of Scarlet Oak in Pennsylvania.
    Plant Disease, 1997
    Co-Authors: Donald D. Davis, Mary L. Torsello, James R. Mcclenahen
    Abstract:

    ABSTRACT Basal cankers induced by Cryphonectria parasitica (=Endothia parasitica) occur throughout the natural range of scarlet oak (Quercus coccinea) within Pennsylvania. Because colonization of scarlet oak is thought to be a long-term host/pathogen relationship, analyses were conducted to investigate effects of basal cankers on radial growth (expressed as area increment) at 1.4 m, breast height (BH). Moderately cankered oaks grew more slowly at BH than did noncankered trees. However, severely cankered scarlet oaks generally exhibited greater radial growth at BH than did noncankered trees. This apparent anomaly likely reflects stimulated growth at BH due to the fungal infection.

  • Incidence of Cryphonectria parasitica cankers on scarlet oak (Quercus coccinea) in Pennsylvania
    Plant Disease, 1994
    Co-Authors: Mary L. Torsello, Donald D. Davis, B. L. Nash
    Abstract:

    Surveys were conducted in Pennsylvania during 1989 and 1990 to determine the distribution and incidence of Cryphonectria parasitica (= Endothia parasitica) cankers on scarlet oak (Quercus coccinea). Cankered scarlet oak were found throughout the natural range, with incidence levels (15.0%) comparable to those previously reported in North Carolina (13.8%). C. parasitica was recovered from 69.7% of attempted isolations. Macroscopic signs (pycnidia or stroma) of C. parasitica were associated with 67% of typical cankers. This represents a significant source of inoculum that may serve to further infect scarlet oaks and also American chestnut sprouts. This is the first report of C. parasitica cankers on scarlet oak in Pennsylvania

Mary L. Torsello - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Cryphonectria parasitica Basal Cankers on Radial Growth of Scarlet Oak in Pennsylvania.
    Plant Disease, 1997
    Co-Authors: Donald D. Davis, Mary L. Torsello, James R. Mcclenahen
    Abstract:

    ABSTRACT Basal cankers induced by Cryphonectria parasitica (=Endothia parasitica) occur throughout the natural range of scarlet oak (Quercus coccinea) within Pennsylvania. Because colonization of scarlet oak is thought to be a long-term host/pathogen relationship, analyses were conducted to investigate effects of basal cankers on radial growth (expressed as area increment) at 1.4 m, breast height (BH). Moderately cankered oaks grew more slowly at BH than did noncankered trees. However, severely cankered scarlet oaks generally exhibited greater radial growth at BH than did noncankered trees. This apparent anomaly likely reflects stimulated growth at BH due to the fungal infection.

  • Incidence of Cryphonectria parasitica cankers on scarlet oak (Quercus coccinea) in Pennsylvania
    Plant Disease, 1994
    Co-Authors: Mary L. Torsello, Donald D. Davis, B. L. Nash
    Abstract:

    Surveys were conducted in Pennsylvania during 1989 and 1990 to determine the distribution and incidence of Cryphonectria parasitica (= Endothia parasitica) cankers on scarlet oak (Quercus coccinea). Cankered scarlet oak were found throughout the natural range, with incidence levels (15.0%) comparable to those previously reported in North Carolina (13.8%). C. parasitica was recovered from 69.7% of attempted isolations. Macroscopic signs (pycnidia or stroma) of C. parasitica were associated with 67% of typical cankers. This represents a significant source of inoculum that may serve to further infect scarlet oaks and also American chestnut sprouts. This is the first report of C. parasitica cankers on scarlet oak in Pennsylvania