The Experts below are selected from a list of 183 Experts worldwide ranked by ideXlab platform
Joan M. Henson - One of the best experts on this subject based on the ideXlab platform.
-
Heavily-melanized variants of the sexual Gaeumannomyces Graminis var. tritici are non-pathogenic and indistinguishable from the asexual, Phialophora state
Fungal Biology, 2002Co-Authors: Tresa Q. Coins, William A. Edens, Joan M. HensonAbstract:Gaeumannomyces Graminis var. tritici is the aetiologic agent of take-all disease of wheat and barley. Heavily-melanized variants of a lightly pigmented, virulent wild-type strain were isolated and characterized. These variants were phenotypically similar to Phialophora sp., the proposed anamorph of Gaeumannomyces Graminis var. tritici. Unlike the wild-type G. Graminis strain, Phialophora-like variants produced conidia and lost their ability to reproduce sexually after serial transfer. Some ascospores from initial self-crosses of the Phialophora-like variants regained the G. Graminis phenotype, and these derivatives could again produce Phialophora-like variants. As with Phialophora isolates from the field, Phialophora-like variants produced in this study were non-pathogenic and produced less extracellular protein.
-
Effect of osmotic stress on growth of Gaeumannomyces Graminis strains differing in hyphal pigmentation
Mycologia, 2001Co-Authors: Monica L. Elliott, Joan M. HensonAbstract:The effect of osmotic stress on mycelial growth was determined for melanized and nonmela- nized strains of Gaeumannomyces Graminis var. tritici and var. Graminis using a minimal salts medium, both in liquid and solid form. The osmotica used were KCl and sucrose. Growth measurements obtained from
-
The fate of integrated DNA in Gaeumannomyces Graminis transformants
Fems Microbiology Letters, 1993Co-Authors: Alice L Pilgeram, Tresa Goins, Joan M. HensonAbstract:The fate of integrated transforming DNA in fungicide (benomyl or phleomycin)-resistant transformants of Gaeumannomyces Graminis was investigated. Transforming DNA was mitotically and meiotically stable in several transformants. However, other transformants of varieties Graminis and tritici were less resistant to fungicide after meiosis. Hybridization analyses indicated that transforming DNA in ascospore progeny had rearrangements and/or deletions, and that similar events could occur during a second meiotic cycle, further reducing their levels of resistance. Rearrangements and/or deletions were most common in transformants with multiple copies of a benomyl-resistance (Benr) plasmid. Transforming sequences were not extensively methylated, even when present in multiple copies.
-
use of polymerase chain reaction to detect Gaeumannomyces Graminis dna in plants grown in artificially and naturally infested soil
Phytopathology, 1993Co-Authors: Joan M. Henson, Tresa Goins, W Grey, D E Mathre, M L ElliottAbstract:The polymerase chain reaction was used to specifically amplify DNA of Gaeumannomyces Graminis, a filamentous soilborne fungus that causes root and crown disease of cereals and turfgrasses. Nested primers were used to amplify a 188-bp fragment of mitochondrial DNA from fungal and infected-plant samples, which were simply boiled to release target DNA. Fungal DNA was amplified from single boiled hyphal tips or ascospores. G. Graminis DNA was also detected in boiled crowns and roots from experimentally and naturally infected wheat, rice, and St. Augustine-grass and experimentally infected bermudagrass []
D M Weller - One of the best experts on this subject based on the ideXlab platform.
-
use of Gaeumannomyces Graminis var Graminis alone and in combination with fluorescent pseudomonas spp to suppress take all of wheat
Plant Disease, 1995Co-Authors: B K Duffy, D M WellerAbstract:Gaeumannomyces Graminis var. Graminis, originally isolated from rice, suppressed take-all of wheat caused by Gaeumannomyces Graminis var. tritici in growth chamber studies when applied to the soil. Furthermore, combination treatments consisting of G. g. var. Graminis applied to the soil and fluorescent Pseudomonas strains applied to the seed, either 30-84, Q29z-80, Q69c-80, or a mixture of strains (Q2-87 plus Q1c-80 plus Q8d-80 plus Q69c-80), were significantly more suppressive of take-all than either treatment used alone. In a winter wheat field trial at Pullman, Wash., G. g. var. Graminis applied to the seed furrow significantly reduced crown root infection by G. g. var. tritici and the strain mixture reduced seminal root infection suggesting differential protection at various stages of disease development. However, in contrast to growth chamber studies the combination of G. g. var. Graminis and the strain mixture did not enhance take-all suppression in the field compared with the same treatments used alone.
-
A semiselective and diagnostic medium for Gaeumannomyces Graminis var. tritici
Phytopathology, 1994Co-Authors: B K Duffy, D M WellerAbstract:Isolation of Gaeumannomyces Graminis var. tritici, causal agent of take-all, from wheat tissues often is complicated by the presence of Pythium spp., Rhizoctonia spp., Fusarium spp. or secondary fungal colonists. Because G. g. tritici does not typically sporulate in culture, identification of putative isolates is based on cultural characteristics, pathogenicity tests, and production of perithecia on infected tissue. A semiselective medium designated R-PDA was developed that aids in the isolation and identification of G. g. tritici. The medium consists of dilute potato-dextrose agar amended with 100 μg ml −1 rifampicin and 10 μg ml −1 tolclofosmethyl. Identification of G. g. tritici is auded based on its ability to alter the color of rifampicin in R-PDA from orange to purple. This reaction occurs in as little as 24 h. R-PDA was more effective in isolating putative isolates of G. g. tritici from wheat with symptoms of take-all than was SM-GGT3, another semiselective medium for G. Graminis var. tritici
David M Weller - One of the best experts on this subject based on the ideXlab platform.
-
diversity virulence and 2 4 diacetylphloroglucinol sensitivity of Gaeumannomyces Graminis var tritici isolates from washington state
Phytopathology, 2009Co-Authors: Younsig Kwak, Timothy C Paulitz, Jennifer Rice, Deborah C M Glandorf, Peter A. H. M. Bakker, David M WellerAbstract:Kwak, Y.-S., Bakker, P. A. H. M., Glandorf, D. C. M., Rice, J. T., Paulitz, T. C., and Weller, D. M. 2009. Diversity, virulence, and 2,4-diacetylphloroglucinol sensitivity of Gaeumannomyces Graminis var. tritici isolates from Washington State. Phytopathology 99:472-479. We determined whether isolates of the take-all pathogen Gaeumannomyces Graminis var. tritici become less sensitive to 2,4-diacetylphloroglucinol (2,4-DAPG) during wheat monoculture as a result of exposure to the antibiotic over multiple growing seasons. Isolates of G. Graminis var. tritici were baited from roots of native grasses collected from noncropped fields and from roots of wheat from fields with different cropping histories near Lind, Ritzville, Pullman, and Almota, WA. Isolates were characterized by using morphological traits, G. Graminis variety-specific polymerase chain reaction and pathogenicity tests. The sensitivity of G. Graminis var. tritici isolates to 2,4-DAPG was determined by measuring radial growth of each isolate. The 90% effective dose value was 3.1 to 4.4 µg ml–1 for 2,4-DAPG-sensitive isolates, 4.5 to 6.1 µg ml–1 for moderately sensitive isolates, and 6.2 to 11.1 µg ml –1 for less sensitive isolates. Sensitivity of G. Graminis var. tritici isolates to 2,4-DAPG was normally distributed in all fields and was not correlated with geographic origin or cropping history of the field. There was no correlation between virulence on wheat and geographical origin, or virulence and sensitivity to 2,4-DAPG. These results indicate that G. Graminis var. tritici does not become less sensitive to 2,4-DAPG during extended wheat monoculture.
-
purification of an antibiotic effective against Gaeumannomyces Graminis var tritici produced by a biocontrol agent pseudomonas aureofaciens
Soil Biology & Biochemistry, 1993Co-Authors: Leslie A Harrison, Leo Joseph Letendre, Peter Kovacevich, Elizabeth A Pierson, David M WellerAbstract:Abstract Inhibition of the fungus that causes take-all of wheat, Gaeumannomyces Graminis (Sacc.) Arx and Oliver var. tritici Walker, by a biocontrol agent, Pseudomonas aureofaciens Q2-87, was demonstrated both in vitro and in vivo. Q2-87 was originally isolated from the rhizosphere of wheat grown in a take-all suppressive soil. An antifungal compound was isolated from a chemically-defined broth culture of strain Q2-87. The structure of the compound was established to be 1,3,6-trihydroxy-2,4-diacetophenone through infrared, [1H]nuclear magnetic resonance (NMR), [113C]NMR, u.v., and high-resolution fast-atom bombardment (FAB) mass spectrometry. The synthesized product of the proposed structure demonstrated activity equal to the purified natural product.
Anne Osbourn - One of the best experts on this subject based on the ideXlab platform.
-
gene expression during infection of wheat roots by the take all fungus Gaeumannomyces Graminis
Molecular Plant Pathology, 2004Co-Authors: M Guilleroux, Anne OsbournAbstract:SUMMARY The infection of plants by pathogenic microbes and the subsequent establishment of disease involves substantial changes in the biochemistry and physiology of both partners. Analysis of genes that are expressed during these interactions represents a powerful strategy to obtain insights into the molecular events underlying these changes. Root diseases have considerable economic impact but have not been characterized extensively at the molecular genetic level. Here we have used two complementary approaches—suppression subtractive hybridization and expressed sequence tag analysis of an unsubtracted cDNA library—to investigate gene expression during the early stages of colonization of wheat roots by the take-all fungus, Gaeumannomyces Graminis.
-
an oat species lacking avenacin is susceptible to infection by Gaeumannomyces Graminis var tritici
Physiological and Molecular Plant Pathology, 1994Co-Authors: Anne Osbourn, Patricia Lunness, P R Scott, B R Clarke, M J DanielsAbstract:The saponin avenacin is a pre-formed inhibitor of fungal growth and occurs in the roots of Avena species. Gaeumannomyces Graminis var. tritici (the causal agent of take-all disease of wheat) is unable to attack oats, apparently because of the sensitivity of this fungus to avenacin. After screening a wide range of oat genotypes, one species, Avena longiglumis , was identified which lacked detectable levels of avenacin and was susceptible to infection by G. Graminis var. tritici , supporting a role for avenacin as a determinant of resistance to fungal attack.
-
Two xylanases from Gaeumannomyces Graminis with identical N-terminal amino acid sequence
Physiological and Molecular Plant Pathology, 1993Co-Authors: S.g. Southerton, Anne Osbourn, J. M. Dow, Michael J. DanielsAbstract:Gaeumannomyces Graminis var. avenae produces extracellular xylanase activity when grown in minimal medium containing xylan as sole carbon source. A 26·5 kDa and a 28 kDa xylanase were isolated from culture filtrates of the fungus grown on xylan. Both xylanases had a pI of 10·5 and behaved very similarly during hydrophobic interaction, cation exchange, and size exclusion chromatography. Enzyme activity of the combined xylanases was maximal at 50 °C and between pH 5·0 and 5·5. The N-terminal amino acid sequences of the two xylanases were identical and showed strong homology with xylanase from Schizophyllum commune and three other microbial xylanases. Xylanase activity with similar properties to the enzymes purified from culture fluids was detected in oat and wheat roots infected with G. Graminis var. avenae but was not detected in healthy roots.
-
partial characterization of avenacinase from Gaeumannomyces Graminis var avenae
Physiological and Molecular Plant Pathology, 1991Co-Authors: Anne Osbourn, B R Clarke, M J DanielsAbstract:The tritici variety of the take-all fungus Gaeumannomyces Graminis causes disease on wheat but is unable to attack oats, while the avenae variety can attack both wheat and oats. The resistance of oats to G. Graminis var. tritici has been attributed to the presence of a pre-formed inhibitor, avenacin. G. Graminis var. avenae isolates are reported to produce an enzyme (avenacinase) which specifically deglucosylates avenacin to less toxic forms. We have verified previous observations that G. Graminis var. avenae isolates are more resistant to avenacin than G. Graminis var. tritici in agar tests. In addition, culture filtrates of isolates of G. Graminis var. avenae have at least 100 times more avenacinase activity than those of isolates of G. Graminis var. tritici . The avenacinase activity of a G. Graminis var. avenae isolate was characterized as a single extracellular protein species of molecular weight 110 kD, by SDS polyacrylamide gel electrophoresis.
B K Duffy - One of the best experts on this subject based on the ideXlab platform.
-
use of Gaeumannomyces Graminis var Graminis alone and in combination with fluorescent pseudomonas spp to suppress take all of wheat
Plant Disease, 1995Co-Authors: B K Duffy, D M WellerAbstract:Gaeumannomyces Graminis var. Graminis, originally isolated from rice, suppressed take-all of wheat caused by Gaeumannomyces Graminis var. tritici in growth chamber studies when applied to the soil. Furthermore, combination treatments consisting of G. g. var. Graminis applied to the soil and fluorescent Pseudomonas strains applied to the seed, either 30-84, Q29z-80, Q69c-80, or a mixture of strains (Q2-87 plus Q1c-80 plus Q8d-80 plus Q69c-80), were significantly more suppressive of take-all than either treatment used alone. In a winter wheat field trial at Pullman, Wash., G. g. var. Graminis applied to the seed furrow significantly reduced crown root infection by G. g. var. tritici and the strain mixture reduced seminal root infection suggesting differential protection at various stages of disease development. However, in contrast to growth chamber studies the combination of G. g. var. Graminis and the strain mixture did not enhance take-all suppression in the field compared with the same treatments used alone.
-
A semiselective and diagnostic medium for Gaeumannomyces Graminis var. tritici
Phytopathology, 1994Co-Authors: B K Duffy, D M WellerAbstract:Isolation of Gaeumannomyces Graminis var. tritici, causal agent of take-all, from wheat tissues often is complicated by the presence of Pythium spp., Rhizoctonia spp., Fusarium spp. or secondary fungal colonists. Because G. g. tritici does not typically sporulate in culture, identification of putative isolates is based on cultural characteristics, pathogenicity tests, and production of perithecia on infected tissue. A semiselective medium designated R-PDA was developed that aids in the isolation and identification of G. g. tritici. The medium consists of dilute potato-dextrose agar amended with 100 μg ml −1 rifampicin and 10 μg ml −1 tolclofosmethyl. Identification of G. g. tritici is auded based on its ability to alter the color of rifampicin in R-PDA from orange to purple. This reaction occurs in as little as 24 h. R-PDA was more effective in isolating putative isolates of G. g. tritici from wheat with symptoms of take-all than was SM-GGT3, another semiselective medium for G. Graminis var. tritici
