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J. A. Kolmer - One of the best experts on this subject based on the ideXlab platform.
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Adapted from: A North American System of Nomenclature for Puccinia triticina
2015Co-Authors: D L Long, J. A. KolmerAbstract:A nomenclature system for designating virulence combinations of cultures of Puccinia triticina (formerly Puccinia recondita f. sp. tritici- (see Taxonomic Change page)) in North America was accepted by th
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Molecular and virulence diversity and linkage disequilibria in asexual and sexual populations of the wheat leaf rust fungus, Puccinia recondita
Genome, 1998Co-Authors: J Q Liu, J. A. KolmerAbstract:An asexual field population and a sexually derived population of the wheat leaf rust fungus, Puccinia recondita, were examined and compared for diversity and linkage disequilibria between virulence...
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physiologic specialization of Puccinia recondita f sp tritici in canada in 1995
Canadian Journal of Plant Pathology-revue Canadienne De Phytopathologie, 1997Co-Authors: J. A. Kolmer, J Q LiuAbstract:In 1995 leaf rust of wheat (Triticum aestivum L.) caused by Puccinia recondita f. sp. tritici was first observed on June 16 in winter wheat fields in southern Manitoba. Warm summer temperatures with frequent dew periods favoured spread of the disease in spring wheat fields throughout southern Manitoba in 1995. High levels of infection were found on wheat cultivars that had only resistance gene Lr13. Wheat cultivars with Lr13 and Lr34 had moderate levels of rust infection, while cultivars with Lr13 or Lr34 plus either Lr21 or Lr16 had very little leaf rust. Forty-six virulence phenotypes of P.r. tritici were identified in 1995 using 16 near-isogenic Thatcher differential lines. Phenotypes with virulence to Lr16 were detected in Manitoba and Saskatchewan for the first time since 1988. Selected isolates were also tested for virulence on adult-plants of isogenic lines with Lr13, Lr34, and Lr13,34. Most isolates were virulent to isolines with Lr13, while all isolates had lower infection type and fewer uredinia on isolines with Lr34 or Lr13,34. Continued increase of virulence to genes Lr13 and Lr16 may erode the leaf rust resistance of recently released western Canada spring wheats.
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virulence in Puccinia recondita f sp tritici isolates from canada to genes for adult plant resistance to wheat leaf rust
Plant Disease, 1997Co-Authors: J. A. KolmerAbstract:Sixty-seven isolates of Puccinia recondita f. sp. tritici collected in Canada were tested for virulence to adult plants of Thatcher near-isogenic wheat lines with leaf rust resistance genes Lr13, Lr22a, Lr34, Lr35, and Lr13 and Lr34 combined. All of the isolates had low infection type to the Thatcher lines with Lr22a and Lr35. All isolates had lower infection type and lower rust severity on the Thatcher line with Lr34 compared with Thatcher. The isolates were polymorphic for virulence to the Thatcher line with Lr13; many isolates were completely virulent to this line, and other isolates produced very low or intermediate avirulent infection type. On the Thatcher line with Lr13 and Lr34 combined, many isolates had infection type and rust severity similar to the Thatcher line with Lr34, while other isolates had lower infection type and rust severity compared with the single-gene lines with Lr13 or Lr34. Fifteen isolates with low, intermediate, and high infection type to adult plants with Lr13 were tested for infection type on seedling plants of the Thatcher lines with resistance genes Lr13, Lr22a, Lr34, Lr35, and Lr37, and on Thatcher lines with Lr13 paired with seedling resistance genes. Most isolates were completely virulent to seedling plants with Lr13 and Lr22a. Plants with Lr37 expressed seedling resistance to all isolates tested. Seedling plants with Lr34 had lower infection types to all isolates compared with Thatcher. Seedlings with Lr35 had high infection types to most isolates, with varying amounts of chlorosis. The Thatcher lines with Lr13 plus seedling resistance genes were most resistant to the isolates that had very low infection types on adult plants with Lr13 and intermediate infection types on plants with seedling resistance genes. Genes Lr22a, Lr35, and Lr37 offer additional sources of highly effective leaf rust resistance in wheat.
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virulence and molecular polymorphism in Puccinia recondita f sp tritici in canada
Phytopathology, 1995Co-Authors: J. A. Kolmer, J Q Liu, M SiesAbstract:Sixty-four representative single-uredinial isolates or Puccinia recondita f. sp. tritici collected from wheat in the eastern (Ontario and Quebec), prairie (Manitoba and Saskatchewan), and Pacific (Alberta and British Columbia) regions of Canada were analyzed for virulence polymorphism on 19 near-isogenic wheat differential lines and for randomly amplified polymorphic DNA (RAPD) using 10 arbitrary decamer primers. Thirty-seven phenotypes or P. r. tritici were distinguished by the 19 host differential lines. Fifteen molecular phenotypes were distinguished by the 10 primers in the RAPD analysis. Forty-five unique phenotypes or P. r. tritici were distinguished by combined virulence and RAPD data. Molecular variation was greatest between isolates or different virulence phenotypes. There was some molecular variation among isolates with identical virulences. Virulence and RAPD data were used separately and combined in cluster analyses. Two major clusters were distinguished with the combined data sets. The first cluster consisted or isolates virulent or avirulent to both resistance genes Lr2a and Lr2c, and the second cluster consisted or isolates avirulent to Lr2a and virulent to Lr2c. The molecular polymorphisms were more effective in distinguishing between the major clusters or P. r. tritici compared to the virulence polymorphisms. However, virulence polymorphisms were more effective in distinguishing between isolates within the major clusters compared to the molecular polymorphisms. There was a correlation or 0,58 between the virulence and molecular dissimilarity matrices. The cluster analyses indicated a general relationship between virulence and molecular polymorphism in P. r. tritici in Canada. There are currently two major groups or P. r. tritici in Canada. One group consists or isolates round in the prairie and eastern regions. Isolates in this group have limited molecular polymorphisms and consist or many virulence phenotypes that are either virulent or avirulent to both Lr2a and Lr2c. Isolates in the second group are round in eastern Canada and in the Pacific region. These isolates are avirulent to Lr2a and virulent to Lr2c and have molecular phenotypes distinct from isolates in the first group. The molecular data support conclusions from virulence survey data that distinct geographic populations or P. r. tritici exist in Canada and that new virulences arise and increase in the prairie population by mutations from preexisting phenotypes
A P Roelfs - One of the best experts on this subject based on the ideXlab platform.
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Puccinia recondita causing leaf rust on cultivated wheats wild wheats and rye
Botany, 1997Co-Authors: Y Anikster, W R Bushnell, T Eilam, J Manisterski, A P RoelfsAbstract:Aecial and telial host range, interfertility, teliospore dimensions, and amount of nuclear DNA were determined for Puccinia recondita collected either worldwide from species of cultivated wheats (Triticum aestivum and Triticum turgidum ssp. durum and rye (Secale cereale), or from wild emmer (Triticum turgidum ssp. dicoccoides) and four species of wild wheat (Aegilops) in Israel. The results indicate that the collections belong in two major groups: Group I (from cultivated wheats and wild emmer), which has Thalictrum speciosissimum (in the Ranunculaceae) as principal aecial host; and Group II (principally from wild wheats or rye), which has several species in the Boraginaceae, such as Anchusa aggregata, Anchusa italica, Echium glomeratum, and Lycopsis arvensis as aecial hosts. In glasshouse experiments, intercrosses could be made readily among collections within Groups I and II but not between the two groups. Group I consisted of all collections from Triticum aestivum, Triticum turgidum ssp. dicoccoides, a...
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virulence and diversity of Puccinia recondita f sp tritici in the united states in 1991
Plant Disease, 1994Co-Authors: D L Long, A P Roelfs, K J Leonard, J J RobertsAbstract:Isolates of Puccinia recondita f. sp. tritici were obtained from wheat leaf collection by cooperators throughout the United States and from cereal rust field surveys of the Great Plains, Ohio Valley, and Gulf Coast states in 1991. Fifty-five virulencelavirulence phenotypes were found among 647 single uredinial isolates on 14 host lines that are isogenic for leaf rust resistance. The frequencies of virulence to lines with Lr24 and Lr26 during 1991 were greater than in previous years. Regional race distribution patterns again suggested that the central United States is a single epidemiological unit distinct from the eastern United States
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pathogenicity of Puccinia recondita f sp tritici in morocco during 1985 1988 1990 and 1992
Plant Disease, 1994Co-Authors: B Ezzahiri, S Diouri, A P RoelfsAbstract:Surveys of pathogenic races of Puccinia recondita f. sp. tritici in Morocco in 1985, 1988, 1990, and 1992 indicated the presence of 12 unified numeration (UN) races. Virulence frequencies were high to Lr1, 2a, 3, 10, 16, and 17 and low to Lrka, 9, 24, and 26. The virulence frequency to Lr2a declined in 1990 and 1992. Isolates from durum wheats were generally less virulent than those from bread wheats to the designated Lr genes in a bread wheat background. The virulence diversity levels were higher in 1990 and 1992 than in 1985 and 1988. The populations with the highest phenotypic diversity were obtained from durum wheat cultivars and the susceptible bread wheat cultivar Siete Cerros
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virulence of Puccinia recondita f sp tritici in the united states during 1988 1990
Plant Disease, 1992Co-Authors: D L Long, A P Roelfs, J J RobertsAbstract:Isolates of Puccinia recondita f. sp. tritici were obtained from wheat leaf collections made by cooperators throughout the United States and from cereal rust field surveys of the Great Plains, Ohio Valley, and Gulf Coast states in 1988, 1989, and 1990. Forty-one virulence/avirulence phenotypes were found among 618 isolates in 1988, 45 among 983 isolates in 1989, and 53 among 906 isolates in 1990 on 14 host lines with single designated genes for leaf rust resistance. The frequencies of virulence to lines with Lr11 and Lr26 during 1988-1990 were greater than in previous years(.)
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diversity of virulence within and among populations of Puccinia recondita f sp tritici in different areas of the united states
Plant Disease, 1992Co-Authors: K J Leonard, A P Roelfs, D L LongAbstract:Data from surveys of pathogenic races of Puccinia recondita f. sp. tritici from 1988 to 1990 were analyzed to compare phenotypic diversity within and among pathogen populations in eight areas of the United States. Collections from nurseries were significantly more diverse than those from commercial fields in five of seven areas. Populations from the southern, central, and northern Great Plains were phenotypically similar. The population from California and other southwestern states was distinctly different from populations from all other areas(.)
D L Long - One of the best experts on this subject based on the ideXlab platform.
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Adapted from: A North American System of Nomenclature for Puccinia triticina
2015Co-Authors: D L Long, J. A. KolmerAbstract:A nomenclature system for designating virulence combinations of cultures of Puccinia triticina (formerly Puccinia recondita f. sp. tritici- (see Taxonomic Change page)) in North America was accepted by th
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virulence and diversity of Puccinia recondita f sp tritici in the united states in 1991
Plant Disease, 1994Co-Authors: D L Long, A P Roelfs, K J Leonard, J J RobertsAbstract:Isolates of Puccinia recondita f. sp. tritici were obtained from wheat leaf collection by cooperators throughout the United States and from cereal rust field surveys of the Great Plains, Ohio Valley, and Gulf Coast states in 1991. Fifty-five virulencelavirulence phenotypes were found among 647 single uredinial isolates on 14 host lines that are isogenic for leaf rust resistance. The frequencies of virulence to lines with Lr24 and Lr26 during 1991 were greater than in previous years. Regional race distribution patterns again suggested that the central United States is a single epidemiological unit distinct from the eastern United States
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virulence of Puccinia recondita f sp tritici in the united states during 1988 1990
Plant Disease, 1992Co-Authors: D L Long, A P Roelfs, J J RobertsAbstract:Isolates of Puccinia recondita f. sp. tritici were obtained from wheat leaf collections made by cooperators throughout the United States and from cereal rust field surveys of the Great Plains, Ohio Valley, and Gulf Coast states in 1988, 1989, and 1990. Forty-one virulence/avirulence phenotypes were found among 618 isolates in 1988, 45 among 983 isolates in 1989, and 53 among 906 isolates in 1990 on 14 host lines with single designated genes for leaf rust resistance. The frequencies of virulence to lines with Lr11 and Lr26 during 1988-1990 were greater than in previous years(.)
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diversity of virulence within and among populations of Puccinia recondita f sp tritici in different areas of the united states
Plant Disease, 1992Co-Authors: K J Leonard, A P Roelfs, D L LongAbstract:Data from surveys of pathogenic races of Puccinia recondita f. sp. tritici from 1988 to 1990 were analyzed to compare phenotypic diversity within and among pathogen populations in eight areas of the United States. Collections from nurseries were significantly more diverse than those from commercial fields in five of seven areas. Populations from the southern, central, and northern Great Plains were phenotypically similar. The population from California and other southwestern states was distinctly different from populations from all other areas(.)
J J Roberts - One of the best experts on this subject based on the ideXlab platform.
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virulence and diversity of Puccinia recondita f sp tritici in the united states in 1991
Plant Disease, 1994Co-Authors: D L Long, A P Roelfs, K J Leonard, J J RobertsAbstract:Isolates of Puccinia recondita f. sp. tritici were obtained from wheat leaf collection by cooperators throughout the United States and from cereal rust field surveys of the Great Plains, Ohio Valley, and Gulf Coast states in 1991. Fifty-five virulencelavirulence phenotypes were found among 647 single uredinial isolates on 14 host lines that are isogenic for leaf rust resistance. The frequencies of virulence to lines with Lr24 and Lr26 during 1991 were greater than in previous years. Regional race distribution patterns again suggested that the central United States is a single epidemiological unit distinct from the eastern United States
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virulence of Puccinia recondita f sp tritici in the united states during 1988 1990
Plant Disease, 1992Co-Authors: D L Long, A P Roelfs, J J RobertsAbstract:Isolates of Puccinia recondita f. sp. tritici were obtained from wheat leaf collections made by cooperators throughout the United States and from cereal rust field surveys of the Great Plains, Ohio Valley, and Gulf Coast states in 1988, 1989, and 1990. Forty-one virulence/avirulence phenotypes were found among 618 isolates in 1988, 45 among 983 isolates in 1989, and 53 among 906 isolates in 1990 on 14 host lines with single designated genes for leaf rust resistance. The frequencies of virulence to lines with Lr11 and Lr26 during 1988-1990 were greater than in previous years(.)
M. G. Eversmeyer - One of the best experts on this subject based on the ideXlab platform.
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triazole seed treatments suppress spore production by Puccinia recondita septoria tritici and stagonospora nodorum from wheat leaves
Plant Disease, 1999Co-Authors: D R Sundin, W W Bockus, M. G. EversmeyerAbstract:ABSTRACT Treatments of winter wheat seed with the systemic triazole fungicides triadimenol (31 g a.i./100 kg = Baytan 30F at 1.5 fl oz/cwt) and difenoconazole (24 g a.i./100 kg = Dividend 3FS at 1.0 fl. oz/cwt) were tested for effect on asexual sporulation by Puccinia recondita, Septoria tritici, and Stagonospora nodorum. Spore production was measured on seedlings grown in a growth chamber (24°C day/15°C night, 12-h photoperiod) and inoculated with the pathogens 3, 5, or 7 weeks after sowing. Spore production was converted to a percentage of the non-treated control and regressed against weeks after planting when plants were inoculated. Linear models fit data for both fungicides against all three pathogens. According to the models, difenoconazole suppressed sporulation levels of P. recondita and Septoria tritici to 10% of the levels on plants from non-treated seed for about 3 weeks after sowing. Spore production for all three fungi was suppressed to 25% of the non-treated level for at least 4.2 weeks and t...
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Survival of Puccinia recondita and P. graminis urediniospores exposed to temperatures from subfreezing to 35 C
Phytopathology, 1995Co-Authors: M. G. Eversmeyer, C. L. KramerAbstract:Viable urediniospores and dormant mycelial infections are the principal inoculum sources that contribute to the establishment and development of destructive wheat rust epidemics in the central Great Plains. Viability of urediniospores of Puccinia recondita and P. graminis was measured by exposure in environmental chambers set at constant temperatures ranging from −6 to 35 C. Exposure of P. recondita and P. graminis urediniospores for up to 120 h to constant temperatures of 5-35 C did not significantly (P ≤ 0.05) affect spore viability among isolates. However, P. recondita and P. graminis urediniospore viability as measured by germination observed after exposure to constant temperatures of -6, −4, −2, 0, 5, 10, 20, 25, 30, or 35 C for 24, 48, 72, 96, or 120 h indicated significant differences in viability among temperature treatment means (P ≤ 0.05). Urediniospores remained viable up to 864 h at constant temperatures between 10 and 30 C and up to 504 h at constant temperatures of 5 and 35 C. Viability of urediniospores exposed at temperatures ranging from −2 to 0 C decreased rapidly after the first 4 h of exposure. At below-freezing temperatures, viability of spores declined rapidly after 1-2 h of exposure. Viability of urediniospores exposed to freezing or below-freezing temperatures was not restored by heat shocking at temperatures typically encountered in the field during an epidemic. Infectivity of P. recondita and P. graminis urediniospores exposed at 5-35 C for 120 h was not significantly different from infectivity of unexposed urediniospores; an average of 58% of the viable urediniospores produced appressoria
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Survival of Puccinia recondita and P. graminis urediniospores as affected by exposure to weather conditions at one meter
Phytopathology, 1994Co-Authors: M. G. Eversmeyer, C. L. KramerAbstract:Viable urediniospores and dormant mycelia are the principal inoculum sources that contribute to the establishment and development of destructive wheat rust epidemics in the central Great Plains of the United States. Inoculum survival was measured by exposing urediniospores of Puccinia recondita and P. graminis to field conditions occurring at 1 m above ground level throughout two crop years. Four phases (summer, fall, winter, and spring) important in survival of urediniospores as potential inoculum in epidemic development were used in data analysis. Survival of P. recondita and P. graminis urediniospores during wheat dormancy (winter) was reduced to 10-11 and 17-21%, respectively, within 24 h [...]
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Effect of temperature on germination and germ-tube development of Puccinia recondita and P. graminis urediniospores
Mycological Research, 1992Co-Authors: C. L. Kramer, M. G. EversmeyerAbstract:Germination of Puccinia recondita and P. graminis urediniospores reached at least 95% within 2 h at temperatures of 6–28 °C. Germination measured in both species was inhibited for at least 4 h at 2°, greatly reduced at 31° and completely inhibited at 35°. Maximum development of P. recondita germ-tubes was recorded at 10, 14 and 22° within 17 h. In contrast, germ-tubes of P. graminis urediniospores developed to maximum lengths at 22 and 25° within 17 h. Lysing of germ-tubes was evident (approximately 2%) within 4 h at all temperatures of 6–31°, but was considerably higher at 31°. Branching and coiling of germ-tubes became more pronounced in both species with increase in temperature after 4 h incubation.
