The Experts below are selected from a list of 516 Experts worldwide ranked by ideXlab platform

Larry D Dunkle - One of the best experts on this subject based on the ideXlab platform.

  • Cercospora Zeae-Maydis: Evidence for Coordinated Host/ Pathogen Responses to Photoperiod?
    2016
    Co-Authors: Purdue E-pubs, Burton H Bluhm, Larry D Dunkle, John B. Ridenour, Hun Kim
    Abstract:

    Cercospora Zeae-Maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. Zeae-Maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. Zeae-Maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1) of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi

  • regulation of stomatal tropism and infection by light in Cercospora zeae maydis evidence for coordinated host pathogen responses to photoperiod
    PLOS Pathogens, 2011
    Co-Authors: John B. Ridenour, Larry D Dunkle, Burton H Bluhm
    Abstract:

    Cercospora Zeae-Maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. Zeae-Maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. Zeae-Maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1) of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi, raising the possibility that C. Zeae-Maydis uses light as a key environmental input to coordinate pathogenesis with maize photoperiodic responses. This study identified a novel molecular mechanism underlying stomatal tropism in a foliar fungal pathogen, provides specific insight into how light regulates pathogenesis in C. Zeae-Maydis, and establishes a genetic framework for the molecular dissection of infection via stomata and the integration of host and pathogen responses to photoperiod.

  • Regulation of stomatal tropism and infection by light in Cercospora Zeae-Maydis: evidence for coordinated host/pathogen responses to photoperiod?
    PLoS pathogens, 2011
    Co-Authors: Hun Kim, John B. Ridenour, Larry D Dunkle, Burton H Bluhm
    Abstract:

    Cercospora Zeae-Maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. Zeae-Maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. Zeae-Maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1) of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi, raising the possibility that C. Zeae-Maydis uses light as a key environmental input to coordinate pathogenesis with maize photoperiodic responses. This study identified a novel molecular mechanism underlying stomatal tropism in a foliar fungal pathogen, provides specific insight into how light regulates pathogenesis in C. Zeae-Maydis, and establishes a genetic framework for the molecular dissection of infection via stomata and the integration of host and pathogen responses to photoperiod.

  • Regulation of Stomatal Tropism and Infection by Light in Cercospora Zeae-Maydis: Evidence for Coordinated Host/ Pathogen Responses to Photoperiod?
    2011
    Co-Authors: Hun Kim, John B. Ridenour, Larry D Dunkle, Burton H Bluhm
    Abstract:

    Cercospora Zeae-Maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. Zeae-Maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. Zeae-Maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1) of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi, raising the possibility that C. Zeae-Maydis uses light as a key environmental input to coordinate pathogenesis with maize photoperiodic responses. This study identified a novel molecular mechanism underlying stomatal tropism in a foliar fungal pathogen, provides specific insight into how light regulates pathogenesis in C. Zeae-Maydis, and establishes a genetic framework for the molecular dissection of infection via stomata and the integration of host and pathogen responses t

  • Analyses of expressed sequence tags from the maize foliar pathogen Cercospora Zeae-Maydis identify novel genes expressed during vegetative, infectious, and reproductive growth.
    BMC genomics, 2008
    Co-Authors: Burton H Bluhm, Braham Dhillon, Erika Lindquist, Gert H. J. Kema, Stephen B. Goodwin, Larry D Dunkle
    Abstract:

    Background The ascomycete fungus Cercospora Zeae-Maydis is an aggressive foliar pathogen of maize that causes substantial losses annually throughout the Western Hemisphere. Despite its impact on maize production, little is known about the regulation of pathogenesis in C. Zeae-Maydis at the molecular level. The objectives of this study were to generate a collection of expressed sequence tags (ESTs) from C. Zeae-Maydis and evaluate their expression during vegetative, infectious, and reproductive growth.

Burton H Bluhm - One of the best experts on this subject based on the ideXlab platform.

  • Cercospora Zeae-Maydis: Evidence for Coordinated Host/ Pathogen Responses to Photoperiod?
    2016
    Co-Authors: Purdue E-pubs, Burton H Bluhm, Larry D Dunkle, John B. Ridenour, Hun Kim
    Abstract:

    Cercospora Zeae-Maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. Zeae-Maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. Zeae-Maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1) of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi

  • regulation of stomatal tropism and infection by light in Cercospora zeae maydis evidence for coordinated host pathogen responses to photoperiod
    PLOS Pathogens, 2011
    Co-Authors: John B. Ridenour, Larry D Dunkle, Burton H Bluhm
    Abstract:

    Cercospora Zeae-Maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. Zeae-Maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. Zeae-Maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1) of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi, raising the possibility that C. Zeae-Maydis uses light as a key environmental input to coordinate pathogenesis with maize photoperiodic responses. This study identified a novel molecular mechanism underlying stomatal tropism in a foliar fungal pathogen, provides specific insight into how light regulates pathogenesis in C. Zeae-Maydis, and establishes a genetic framework for the molecular dissection of infection via stomata and the integration of host and pathogen responses to photoperiod.

  • Regulation of stomatal tropism and infection by light in Cercospora Zeae-Maydis: evidence for coordinated host/pathogen responses to photoperiod?
    PLoS pathogens, 2011
    Co-Authors: Hun Kim, John B. Ridenour, Larry D Dunkle, Burton H Bluhm
    Abstract:

    Cercospora Zeae-Maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. Zeae-Maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. Zeae-Maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1) of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi, raising the possibility that C. Zeae-Maydis uses light as a key environmental input to coordinate pathogenesis with maize photoperiodic responses. This study identified a novel molecular mechanism underlying stomatal tropism in a foliar fungal pathogen, provides specific insight into how light regulates pathogenesis in C. Zeae-Maydis, and establishes a genetic framework for the molecular dissection of infection via stomata and the integration of host and pathogen responses to photoperiod.

  • Regulation of Stomatal Tropism and Infection by Light in Cercospora Zeae-Maydis: Evidence for Coordinated Host/ Pathogen Responses to Photoperiod?
    2011
    Co-Authors: Hun Kim, John B. Ridenour, Larry D Dunkle, Burton H Bluhm
    Abstract:

    Cercospora Zeae-Maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. Zeae-Maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. Zeae-Maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1) of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi, raising the possibility that C. Zeae-Maydis uses light as a key environmental input to coordinate pathogenesis with maize photoperiodic responses. This study identified a novel molecular mechanism underlying stomatal tropism in a foliar fungal pathogen, provides specific insight into how light regulates pathogenesis in C. Zeae-Maydis, and establishes a genetic framework for the molecular dissection of infection via stomata and the integration of host and pathogen responses t

  • Analyses of expressed sequence tags from the maize foliar pathogen Cercospora Zeae-Maydis identify novel genes expressed during vegetative, infectious, and reproductive growth.
    BMC genomics, 2008
    Co-Authors: Burton H Bluhm, Braham Dhillon, Erika Lindquist, Gert H. J. Kema, Stephen B. Goodwin, Larry D Dunkle
    Abstract:

    Background The ascomycete fungus Cercospora Zeae-Maydis is an aggressive foliar pathogen of maize that causes substantial losses annually throughout the Western Hemisphere. Despite its impact on maize production, little is known about the regulation of pathogenesis in C. Zeae-Maydis at the molecular level. The objectives of this study were to generate a collection of expressed sequence tags (ESTs) from C. Zeae-Maydis and evaluate their expression during vegetative, infectious, and reproductive growth.

P. E. Lipps - One of the best experts on this subject based on the ideXlab platform.

  • Heritability and Components of Resistance to Cercospora Zeae-Maydis Derived from Maize Inbred VO613Y.
    Phytopathology, 2006
    Co-Authors: Stuart G. Gordon, P. E. Lipps, Richard C. Pratt
    Abstract:

    ABSTRACT Gray leaf spot (GLS), caused by the fungus Cercospora Zeae-Maydis, is one of the most important foliar diseases of maize. This study was undertaken to estimate heritability of C. Zeae-Maydis resistance and examine the relationship between previously identified resistance loci and certain components of resistance including incubation period, lesion number, and maximum lesion length. Partially inbred progenies arising from hybridization between maize inbred lines VO613Y (high level of partial resistance) and Pa405 (susceptible) were examined in Ohio and South Africa. Heritability estimates of resistance were calculated based on severity and incubation period values. The range of heritability estimates based on severity was broad, with values ranging from approximately 0.46 to 0.81 (mean = 0.59). Estimates of mean heritability for incubation period were lowest (0.18), indicating that this component would likely be unsuitable for selection of germ plasm intended for deployment in diverse regions. Len...

  • Development of Greenhouse Inoculation Procedures for Evaluation of Partial Resistance to Cercospora Zeae-Maydis in Maize Inbreds
    Journal of Phytopathology, 2005
    Co-Authors: Godfrey Asea, P. E. Lipps, Richard C. Pratt, Stuart G. Gordon, E. Adipala
    Abstract:

    Greenhouse experiments were conducted to determine the effects of inoculation methods on incubation period, lesion length, percentage leaf area affected and sporulation of Cercospora Zeae-Maydis on young maize (Zea mays L.) plants inoculated at V3 growth stage. Seedling plants were inoculated by four methods: (i) application of conidial suspension while puncturing the leaves within the whorl several times, (ii) spraying conidial suspension on leaves, (iii) placing colonized agar into lateral slits in leaves and (iv) placing colonized agar into whorls. Analysis of variance revealed a significant effect of genotype and inoculation method on several components of resistance and overall disease severity. Application of conidial suspension while puncturing the whorl was found to be the least laborious method, and it produced characteristic symptoms of gray leaf spot. Consistent trends were observed in classification of inbreds to resistant, susceptible and intermediate classes. Increasing the duration of exposure to high humidity by placing plastic bags over plants for 5 days significantly increased disease severity (P ≤ 0.001). Cercospora Zeae-Maydis produced conidia in all the lesions examined. Spore production was generally most abundant in lesions on susceptible inbreds that displayed necrotic lesion types (LT) and least abundant in lesions on resistant inbreds that were characterized by chlorotic and fleck LTs. The results demonstrated that inoculations in the greenhouse can provide an indication of inbred responses to C. Zeae-Maydis and may be useful in evaluating resistance and in studies of host–pathogen interactions.

  • linkage of molecular markers to Cercospora zeae maydis resistance in maize
    Crop Science, 2004
    Co-Authors: Stuart G. Gordon, P. E. Lipps, Michael Bartsch, Inge Matthies, Hans O Gevers, Richard C. Pratt
    Abstract:

    Gray leaf spot (GLS) of maize (Zea mays L.) caused by Cercospora Zeae-Maydis Tehon & E.Y. Daniels, can greatly reduce grain yield in conducive environments worldwide. This study was undertaken to evaluate a novel source of resistance to C. Zeae-Maydis across macroenvironments and link molecular markers to resistance loci by selective genotyping. A population of 144 F 2:3 progeny lines derived from a cross between resistant maize inbred V0613Y and susceptible inbred Pa405 were evaluated at Wooster, OH, USA, and Cedara Agricultural Research Institute, Department of Agriculture, KZN, Republic of South Africa (RSA), for resistance to C. Zeae-Maydis. The lines were assigned to phenotypic classes (resistant, intermediate, and susceptible) on the basis of percent leaf area affected (PLAA) values across environments. F 2:4 progeny lines were produced by controlled self-pollination of an individual plant within each F 2:3 line. F 2:4 lines derived from resistant and susceptible classes were evaluated at two Ohio locations. The same lines, plus a random sample of 54 F 2:4 lines representing the intermediate class, were evaluated at Cedara. Molecular marker data were analyzed on the basis of PLAA means of F 2:4 progenies by Kruskal-Wallis analysis and several markers on chromosomes 2 and 4 were deemed to be significantly associated with resistance. Additional molecular markers were added and composite interval mapping was conducted on genetic maps of those chromosomes. Quantitative trait loci (QTL) located on chromosome arms 2L and 4L together explained 40 to 47% of the phenotypic variation. A resistance gene analog probe flanked the significant interval on chromosome 4L. These intervals on chromosomes 2L and 4L were detected in all tests and we consider them to be suitable candidate QTL for marker-assisted selection (MAS). These results indicate that V0613Y is a source of resistance with potential to be deployed effectively in both southern Africa and the U.S. Corn Belt.

  • Linkage of Molecular Markers to Cercospora zeae‐maydis Resistance in Maize
    Crop Science, 2004
    Co-Authors: Stuart G. Gordon, P. E. Lipps, Michael Bartsch, Inge Matthies, Hans O Gevers, Richard C. Pratt
    Abstract:

    Gray leaf spot (GLS) of maize (Zea mays L.) caused by Cercospora Zeae-Maydis Tehon & E.Y. Daniels, can greatly reduce grain yield in conducive environments worldwide. This study was undertaken to evaluate a novel source of resistance to C. Zeae-Maydis across macroenvironments and link molecular markers to resistance loci by selective genotyping. A population of 144 F 2:3 progeny lines derived from a cross between resistant maize inbred V0613Y and susceptible inbred Pa405 were evaluated at Wooster, OH, USA, and Cedara Agricultural Research Institute, Department of Agriculture, KZN, Republic of South Africa (RSA), for resistance to C. Zeae-Maydis. The lines were assigned to phenotypic classes (resistant, intermediate, and susceptible) on the basis of percent leaf area affected (PLAA) values across environments. F 2:4 progeny lines were produced by controlled self-pollination of an individual plant within each F 2:3 line. F 2:4 lines derived from resistant and susceptible classes were evaluated at two Ohio locations. The same lines, plus a random sample of 54 F 2:4 lines representing the intermediate class, were evaluated at Cedara. Molecular marker data were analyzed on the basis of PLAA means of F 2:4 progenies by Kruskal-Wallis analysis and several markers on chromosomes 2 and 4 were deemed to be significantly associated with resistance. Additional molecular markers were added and composite interval mapping was conducted on genetic maps of those chromosomes. Quantitative trait loci (QTL) located on chromosome arms 2L and 4L together explained 40 to 47% of the phenotypic variation. A resistance gene analog probe flanked the significant interval on chromosome 4L. These intervals on chromosomes 2L and 4L were detected in all tests and we consider them to be suitable candidate QTL for marker-assisted selection (MAS). These results indicate that V0613Y is a source of resistance with potential to be deployed effectively in both southern Africa and the U.S. Corn Belt.

  • Effect of Cercospora Zeae-Maydis infested maize residue on progress and spread of grey leaf spot of maize in central Uganda
    Annals of Applied Biology, 2002
    Co-Authors: Godfrey Asea, Richard C. Pratt, E. Adipala, George Bigirwa, S. A. P. Owera, P. E. Lipps
    Abstract:

    Summary The spread of grey leaf spot caused by Cercospora Zeae-Maydis from infested maize residue on the soil surface and progress over time were studied under tropical conditions at two locations in central Uganda, Kabanyolo and Namulonge, using a susceptible local cultivar, LP16. Infested maize residue collected the previous season was used as the inoculum source in varying amounts; 80% coverage, 40% coverage and 0% soil coverage were used to simulate no tillage, minimum tillage and maximum tillage with complete burial of residues. In all the seasons, disease spread was adequately described by a power law model, whereas disease progress over time was equally well represented by both Gompertz and logistic models. The time factor was highly significant (P < 0.05) for disease development, indicating both increases in disease intensity over time and change in gradients with time. The amount of infested residue on the soil surface in the maize planting was highly significant (P < 0.05) for slope (b) and intercept (a) of the linearised disease gradient. The gradient parameter (b) based on the average for the four directions from the residue source ranged from −0.96 to −0.08 in the second cropping season of 1999, from −2.16 to −0.01 and from −0.87 to −0.03 in the first and second seasons of 2000, respectively. The distance from the infested residue significantly affected foliar disease, but the direction from the residue inoculum source did not, nor was the distance by direction interaction significant. However, interactions between amount of residue and distance were significant. Percentage leaf area affected by grey leaf spot, the areas under disease progress curves and disease intercepts decreased with distance at both locations, but rate of disease increase (r) was generally constant with distance from residue source at Kabanyolo, but not at Namulonge. The relationship between disease severity and amount of residue cover appeared to be affected by the level of background inoculum. At Kabanyolo, where little background inoculum was present, differences were detected in disease severity parameters between the no-residue plots and residue plots, whereas at Namulonge, where high background levels existed, there was no effect of residue on disease.

Richard C. Pratt - One of the best experts on this subject based on the ideXlab platform.

  • Infection process in resistant and susceptible maize (Zea mays L.) genotypes to Cercospora Zeae-Maydis (type II).
    Plant protection science, 2018
    Co-Authors: H.j.f. Lyimo, Richard C. Pratt, R.s.o.w. Mnyuku
    Abstract:

    Lyimo H.J.F., Pratt R.C., Mnyuku R.S.O.W. (2013): Infection process in resistant and susceptible maize (Zea mays L.) genotypes to Cercospora Zeae-Maydis (type II). Plant Protect. Sci., 49: 11–18. The infection process of Cercospora zeae-maydi s type II (syn. Cercospora zeina Meisel and Korsman) in resistant, moderately resistant and susceptible maize genotypes was studied in the greenhouse under artificial inoculation. The percent spore germination, germ tube growth and formation of mature appressorium on leaves at 24, 36, 48, and 72 h after inoculation did not differ between resistant, moderately resistant, and susceptible maize genotypes ( P ≤ 0.05). More germlings were established after penetration on susceptible than resistant and moderately resistant maize genotypes at 72, 96, 120, and 144 h after inoculation. The hyphal wefts in cells of resistant and moderately resistant genotypes were shorter than in susceptible genotypes ( P ≤ 0.05). The slow pathogen growth was associated with a reduced number of conidiophores per stroma, spores per unit area and smaller lesions. The reduced pathogen growth after penetration suggests possible involvement of pathogen growth inhibitory substances in maize resistance to C. Zeae-Maydis type II .

  • Heritability and Components of Resistance to Cercospora Zeae-Maydis Derived from Maize Inbred VO613Y.
    Phytopathology, 2006
    Co-Authors: Stuart G. Gordon, P. E. Lipps, Richard C. Pratt
    Abstract:

    ABSTRACT Gray leaf spot (GLS), caused by the fungus Cercospora Zeae-Maydis, is one of the most important foliar diseases of maize. This study was undertaken to estimate heritability of C. Zeae-Maydis resistance and examine the relationship between previously identified resistance loci and certain components of resistance including incubation period, lesion number, and maximum lesion length. Partially inbred progenies arising from hybridization between maize inbred lines VO613Y (high level of partial resistance) and Pa405 (susceptible) were examined in Ohio and South Africa. Heritability estimates of resistance were calculated based on severity and incubation period values. The range of heritability estimates based on severity was broad, with values ranging from approximately 0.46 to 0.81 (mean = 0.59). Estimates of mean heritability for incubation period were lowest (0.18), indicating that this component would likely be unsuitable for selection of germ plasm intended for deployment in diverse regions. Len...

  • Development of Greenhouse Inoculation Procedures for Evaluation of Partial Resistance to Cercospora Zeae-Maydis in Maize Inbreds
    Journal of Phytopathology, 2005
    Co-Authors: Godfrey Asea, P. E. Lipps, Richard C. Pratt, Stuart G. Gordon, E. Adipala
    Abstract:

    Greenhouse experiments were conducted to determine the effects of inoculation methods on incubation period, lesion length, percentage leaf area affected and sporulation of Cercospora Zeae-Maydis on young maize (Zea mays L.) plants inoculated at V3 growth stage. Seedling plants were inoculated by four methods: (i) application of conidial suspension while puncturing the leaves within the whorl several times, (ii) spraying conidial suspension on leaves, (iii) placing colonized agar into lateral slits in leaves and (iv) placing colonized agar into whorls. Analysis of variance revealed a significant effect of genotype and inoculation method on several components of resistance and overall disease severity. Application of conidial suspension while puncturing the whorl was found to be the least laborious method, and it produced characteristic symptoms of gray leaf spot. Consistent trends were observed in classification of inbreds to resistant, susceptible and intermediate classes. Increasing the duration of exposure to high humidity by placing plastic bags over plants for 5 days significantly increased disease severity (P ≤ 0.001). Cercospora Zeae-Maydis produced conidia in all the lesions examined. Spore production was generally most abundant in lesions on susceptible inbreds that displayed necrotic lesion types (LT) and least abundant in lesions on resistant inbreds that were characterized by chlorotic and fleck LTs. The results demonstrated that inoculations in the greenhouse can provide an indication of inbred responses to C. Zeae-Maydis and may be useful in evaluating resistance and in studies of host–pathogen interactions.

  • linkage of molecular markers to Cercospora zeae maydis resistance in maize
    Crop Science, 2004
    Co-Authors: Stuart G. Gordon, P. E. Lipps, Michael Bartsch, Inge Matthies, Hans O Gevers, Richard C. Pratt
    Abstract:

    Gray leaf spot (GLS) of maize (Zea mays L.) caused by Cercospora Zeae-Maydis Tehon & E.Y. Daniels, can greatly reduce grain yield in conducive environments worldwide. This study was undertaken to evaluate a novel source of resistance to C. Zeae-Maydis across macroenvironments and link molecular markers to resistance loci by selective genotyping. A population of 144 F 2:3 progeny lines derived from a cross between resistant maize inbred V0613Y and susceptible inbred Pa405 were evaluated at Wooster, OH, USA, and Cedara Agricultural Research Institute, Department of Agriculture, KZN, Republic of South Africa (RSA), for resistance to C. Zeae-Maydis. The lines were assigned to phenotypic classes (resistant, intermediate, and susceptible) on the basis of percent leaf area affected (PLAA) values across environments. F 2:4 progeny lines were produced by controlled self-pollination of an individual plant within each F 2:3 line. F 2:4 lines derived from resistant and susceptible classes were evaluated at two Ohio locations. The same lines, plus a random sample of 54 F 2:4 lines representing the intermediate class, were evaluated at Cedara. Molecular marker data were analyzed on the basis of PLAA means of F 2:4 progenies by Kruskal-Wallis analysis and several markers on chromosomes 2 and 4 were deemed to be significantly associated with resistance. Additional molecular markers were added and composite interval mapping was conducted on genetic maps of those chromosomes. Quantitative trait loci (QTL) located on chromosome arms 2L and 4L together explained 40 to 47% of the phenotypic variation. A resistance gene analog probe flanked the significant interval on chromosome 4L. These intervals on chromosomes 2L and 4L were detected in all tests and we consider them to be suitable candidate QTL for marker-assisted selection (MAS). These results indicate that V0613Y is a source of resistance with potential to be deployed effectively in both southern Africa and the U.S. Corn Belt.

  • Linkage of Molecular Markers to Cercospora zeae‐maydis Resistance in Maize
    Crop Science, 2004
    Co-Authors: Stuart G. Gordon, P. E. Lipps, Michael Bartsch, Inge Matthies, Hans O Gevers, Richard C. Pratt
    Abstract:

    Gray leaf spot (GLS) of maize (Zea mays L.) caused by Cercospora Zeae-Maydis Tehon & E.Y. Daniels, can greatly reduce grain yield in conducive environments worldwide. This study was undertaken to evaluate a novel source of resistance to C. Zeae-Maydis across macroenvironments and link molecular markers to resistance loci by selective genotyping. A population of 144 F 2:3 progeny lines derived from a cross between resistant maize inbred V0613Y and susceptible inbred Pa405 were evaluated at Wooster, OH, USA, and Cedara Agricultural Research Institute, Department of Agriculture, KZN, Republic of South Africa (RSA), for resistance to C. Zeae-Maydis. The lines were assigned to phenotypic classes (resistant, intermediate, and susceptible) on the basis of percent leaf area affected (PLAA) values across environments. F 2:4 progeny lines were produced by controlled self-pollination of an individual plant within each F 2:3 line. F 2:4 lines derived from resistant and susceptible classes were evaluated at two Ohio locations. The same lines, plus a random sample of 54 F 2:4 lines representing the intermediate class, were evaluated at Cedara. Molecular marker data were analyzed on the basis of PLAA means of F 2:4 progenies by Kruskal-Wallis analysis and several markers on chromosomes 2 and 4 were deemed to be significantly associated with resistance. Additional molecular markers were added and composite interval mapping was conducted on genetic maps of those chromosomes. Quantitative trait loci (QTL) located on chromosome arms 2L and 4L together explained 40 to 47% of the phenotypic variation. A resistance gene analog probe flanked the significant interval on chromosome 4L. These intervals on chromosomes 2L and 4L were detected in all tests and we consider them to be suitable candidate QTL for marker-assisted selection (MAS). These results indicate that V0613Y is a source of resistance with potential to be deployed effectively in both southern Africa and the U.S. Corn Belt.

Gary P Munkvold - One of the best experts on this subject based on the ideXlab platform.

  • influence of temperature and relative humidity on sporulation of Cercospora zeae maydis and expansion of gray leaf spot lesions on maize leaves
    Plant Disease, 2005
    Co-Authors: P A Paul, Gary P Munkvold
    Abstract:

    ABSTRACT Controlled environment studies were conducted to determine the effects of temperature on the expansion of lesions of gray leaf spot, and the effects of temperature and relative humidity on the sporulation of Cercospora Zeae-Maydis on maize (Zea mays). For the lesion expansion experiment, potted maize plants were spray inoculated at growth stage V6, bagged, and incubated at 25 to 28°C and 100% relative humidity for 36 to 40 h. Symptomatic plants were transferred to growth chambers and exposed to constant temperatures of 25, 30, and 35°C. Lesion area (length by width) was measured at 4-day intervals for 17 days. For sporulation studies, lesions were excised from naturally infected maize leaves, measured, and incubated at constant temperature (20, 25, 30, or 35°C) and relative humidity (70, 80, 90, or 100%) for 72 h. Sporulation was estimated as the number of conidia per square centimeter of diseased leaf tissue. A quadratic function was used to model the relationship between log-transformed conidia...

  • Regression and artificial neural network modeling for the prediction of gray leaf spot of maize.
    Phytopathology, 2005
    Co-Authors: Pierce A. Paul, Gary P Munkvold
    Abstract:

    ABSTRACT Regression and artificial neural network (ANN) modeling approaches were combined to develop models to predict the severity of gray leaf spot of maize, caused by Cercospora Zeae-Maydis. In all, 329 cases consisting of environmental, cultural, and location-specific variables were collected for field plots in Iowa between 1998 and 2002. Disease severity on the ear leaf at the dough to dent plant growth stage was used as the response variable. Correlation and regression analyses were performed to select potentially useful predictor variables. Predictors from the best 9 of 80 regression models were used to develop ANN models. A random sample of 60% of the cases was used to train the networks, and 20% each for testing and validation. Model performance was evaluated based on coefficient of determination (R2) and mean square error (MSE) for the validation data set. The best models had R2 ranging from 0.70 to 0.75 and MSE ranging from 174.7 to 202.8. The most useful predictor variables were hours of daily...

  • A model-based approach to preplanting risk assessment for gray leaf spot of maize.
    Phytopathology, 2004
    Co-Authors: Pierce A. Paul, Gary P Munkvold
    Abstract:

    ABSTRACT Risk assessment models for gray leaf spot of maize, caused by Cercospora Zeae-Maydis, were developed using preplanting site and maize genotype data as predictors. Disease severity at the dough/dent plant growth stage was categorized into classes and used as the response variable. Logistic regression and classification and regression tree (CART) modeling approaches were used to predict severity classes as a function of planting date (PD), amount of maize soil surface residue (SR), cropping sequence, genotype maturity and gray leaf spot resistance (GLSR) ratings, and longitude (LON). Models were development using 332 cases collected between 1998 and 2001. Thirty cases collected in 2002 were used to validate the models. Preplanting data showed a strong relationship with late-season gray leaf spot severity classes. The most important predictors were SR, PD, GLSR, and LON. Logistic regression models correctly classified 60 to 70% of the validation cases, whereas the CART models correctly classified 57...

  • Relationships of Environmental and Cultural Factors with Severity of Gray Leaf Spot in Maize
    Plant disease, 2002
    Co-Authors: Alka Bhatia, Gary P Munkvold
    Abstract:

    ABSTRACT Gray leaf spot of maize caused by Cercospora Zeae-Maydis is a major foliar disease in the United States and other parts of the world. Efficient management of gray leaf spot is hindered by a lack of quantitative information regarding environmental and cultural influences on disease severity. We collected environmental, cultural, and disease severity data in southern Iowa at 13 locations in 1998 and 11 locations in 1999. The independent variables that we considered included temperature, relative humidity, leaf wetness, percent maize residue cover, distance to nearest maize residue, planting date, and previous crop. A time-duration value (TDV) variable was created to represent cumulative hours of favorable temperature (22 ≤ T ≤ 30°C) and relative humidity (≥95%). Disease severity was assessed at 2-week intervals on three to eight maize genotypes differing in gray leaf spot resistance and maturity at each location. Environmental, cultural, and disease data were summarized for four different periods d...

  • Probabilities for profitable fungicide use against gray leaf spot in hybrid maize.
    Phytopathology, 2001
    Co-Authors: Gary P Munkvold, C.a. Martinson, J. M. Shriver, P. M. Dixon
    Abstract:

    ABSTRACT Gray leaf spot, caused by the fungus Cercospora Zeae-Maydis, causes considerable yield losses in hybrid maize grown in the north-central United States and elsewhere. Nonchemical management tactics have not adequately prevented these losses. The probability of profitably using fungicide application as a management tool for gray leaf spot was evaluated in 10 field experiments under conditions of natural inoculum in Iowa. Gray leaf spot severity in untreated control plots ranged from 2.6 to 72.8% for the ear leaf and from 3.0 to 7.7 (1 to 9 scale) for whole-plot ratings. In each experiment, fungicide applications with propiconazole or mancozeb significantly reduced gray leaf spot severity. Fungicide treatment significantly (P ≤ 0.05) increased yield by as much as 1.65 t/ha with a single propiconazole application. There were significant (P < 0.05) correlations between gray leaf spot severity and yield. We used a Bayesian inference method to calculate for each experiment the probability of achieving a...