scholarly journals Analysis of epidermis- and mesophyll-specific transcript accumulation in powdery mildew-inoculated wheat leaves

2005 ◽  
Vol 58 (2) ◽  
pp. 247-267 ◽  
Author(s):  
Rémy Bruggmann ◽  
Olaf Abderhalden ◽  
Philippe Reymond ◽  
Robert Dudler
Keyword(s):  
Powdery Mildew ◽  
Transcript Accumulation ◽  
Specific Transcript ◽  
Wheat Leaves ◽  
Mesophyll Specific

scholarly journals Virulence Structure of the Eastern U.S. Wheat Powdery Mildew Population

Plant Disease ◽  
2008 ◽  
Vol 92 (7) ◽  
pp. 1074-1082 ◽  
Author(s):  
Ryan Parks ◽  
Ignazio Carbone ◽  
J. Paul Murphy ◽  
David Marshall ◽  
Christina Cowger
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Geographic Distance ◽  
Restricted Gene Flow ◽  
Eastern United States ◽  
Phenotypic Differences ◽  
Wheat Powdery Mildew ◽  
Detached Leaves ◽  
Geographic Separation ◽  
Wheat Leaves

Little is known about the population structure of wheat powdery mildew in the eastern United States, and the most recent report on virulence in this population involved isolates collected in 1993–94. In the present study, wheat leaves naturally infected with powdery mildew were collected from 10 locations in the southeastern United States in 2003 and 2005 and a collection of 207 isolates was derived from single ascospores. Frequencies of virulence to 16 mildew resistance (Pm) genes were determined by inoculating the isolates individually on replicated plates of detached leaves of differential wheat lines. These virulence frequencies were used to infer local effectiveness of Pm genes, estimate virulence complexity, detect significant associations between pairs of pathogen avirulence loci, and assess whether phenotypic differences between pathogen subpopulations increased with geographic distance. In both years, virulence to Pm3a, Pm3c, Pm5a, and Pm7 was present in more than 90% of sampled isolates and virulence to Pm1a, Pm16, Pm17, and Pm25 was present in fewer than 10% of isolates. In each year, 71 to 88% of all sampled isolates possessed one of a few multilocus virulence phenotypes, although there were significant differences among locations in frequencies of virulence to individual Pm genes. Several significant associations were detected between alleles for avirulence to pairs of Pm genes. Genetic (phenotypic) distance between isolate subpopulations increased significantly (R2 = 0.40, P < 0.001) with increasing geographic separation; possible explanations include different commercial deployment of Pm genes and restricted gene flow in the pathogen population.

scholarly journals Effect of Abscisic Acid on the Susceptibility of Wheat Leaves to Powdery Mildew Blumeria graminis f. sp. tritici

2020 ◽  
pp. 164-172
Author(s):  
Alexander V. Babosha
Keyword(s):  
Abscisic Acid ◽  
Powdery Mildew ◽  
Concentration Dependence ◽  
Blumeria Graminis ◽  
Negative Regulator ◽  
Complex Nature ◽  
Exogenous Aba ◽  
Wide Range ◽  
Immunomodulatory Properties ◽  
Wheat Leaves

Abscisic acid (ABA) plays an important role in the regulation of protective processes under stresses of various nature. In contrast to abiotic stresses, when a plant and a pathogen interact, this phytohormone is in most cases a negative regulator of resistance. However, even with a similar nature of pathogenesis, ABA can produce different effects. For example, ABA treatment in different experiments induced either a decrease or an increase in the susceptibility of cereals to powdery mildew. The aim of this work was to study the immunomodulatory properties of exogenous ABA depending on its concentration in the pathosystem composed of wheat Triticum aestivum L. plants and powdery mildew pathogen Blumeria graminis (DC.) Speer f. sp. tritici (syn. Erysiphe graminis). We studied the change in the number of pathogen colonies on susceptible wheat leaves (Zarya and Tavrichanka varieties) when two-week-old seedlings were treated with various ABA concentrations (0–9 μM) before and immediately after they were infected. When whole plants were used in the experiment, ABA was added to Knop’s solution; in experiments with detached leaves floating in Petri dishes, aqueous solutions of the phytohormone were used. Our results show that the magnitude and direction of the effect of exogenous ABA on the number of colonies of the pathogen depends on its concentration and the time of application relative to the moment of infection. ABA concentration dependence was variable in form: similar concentrations could be inhibitory, resulting in the minimum number of colonies, or stimulating, with the maximum number of colonies. At the same time, the pre-infection use of ABA was more likely to be inhibitory. The non-monotonicity and variation of the form of concentration dependence could probably account for the contradictory literature data on the immunomodulatory properties of ABA. The complex nature of the concentration dependence and the corresponding variation in the immunological state within a fairly wide range seem to ensure the Abscisic acid (ABA) plays an important role in the regulation of protective processes under stresses of various nature. In contrast to abiotic stresses, when a plant and a pathogen interact, this phytohormone is in most cases a negative regulator of resistance. However, even with a similar nature of pathogenesis, ABA can produce different effects. For example, ABA treatment in different experiments induced either a decrease or an increase in the susceptibility of cereals to powdery mildew. The aim of this work was to study the immunomodulatory properties of exogenous ABA depending on its concentration in the pathosystem composed of wheat Triticum aestivum L. plants and powdery mildew pathogen Blumeria graminis (DC.) Speer f. sp. tritici (syn. Erysiphe graminis). We studied the change in the number of pathogen colonies on susceptible wheat leaves (Zarya and Tavrichanka varieties) when two-week-old seedlings were treated with various ABA concentrations (0–9 μM) before and immediately after they were infected. When whole plants were used in the experiment, ABA was added to Knop’s solution; in experiments with detached leaves floating in Petri dishes, aqueous solutions of the phytohormone were used. Our results show that the magnitude and direction of the effect of exogenous ABA on the number of colonies of the pathogen depends on its concentration and the time of application relative to the moment of infection. ABA concentration dependence was variable in form: similar concentrations could be inhibitory, resulting in the minimum number of colonies, or stimulating, with the maximum number of colonies. At the same time, the pre-infection use of ABA was more likely to be inhibitory. The non-monotonicity and variation of the form of concentration dependence could probably account for the contradictory literature data on the immunomodulatory properties of ABA. The complex nature of the concentration dependence and the corresponding variation in the immunological state within a fairly wide range seem to ensure themaintenance of equilibrium in the pathosystem and the chances for survival of both the host plant and the pathogen.

scholarly journals An important role for secreted esterase in disease establishment of the wheat powdery mildew fungus Blumeria graminis f. sp.tritici

2011 ◽  
Vol 57 (3) ◽  
pp. 211-216 ◽  
Author(s):  
Jie Feng ◽  
Feng Wang ◽  
Geoff R. Hughes ◽  
Susan Kaminskyj ◽  
Yangdou Wei
Keyword(s):  
Powdery Mildew ◽  
Blumeria Graminis ◽  
Powdery Mildew Fungus ◽  
Diisopropyl Fluorophosphate ◽  
Wheat Powdery Mildew ◽  
Leaf Surfaces ◽  
Indigo Blue ◽  
Serine Esterases ◽  
Wheat Leaves

The activity of esterase secreted by conidia of wheat powdery mildew fungus, Blumeria graminis f. sp. tritici, was assayed using indoxyl acetate hydrolysis, which generates indigo blue crystals. Mature, ungerminated, and germinating conidia secrete esterase(s) on artificial media and on plant leaf surfaces. The activity of these esterases was inhibited by diisopropyl fluorophosphate, which is selective for serine esterases. When conidia were inoculated on wheat leaves pretreated with diisopropyl fluorophosphate, both appressorial germ tube differentiation and symptom development were significantly impaired, indicating an important role of secreted serine esterases in wheat powdery mildew disease establishment.

Application of Continuum Removal Method for Estimating Disease Severity Level of Wheat Powdery Mildew

2011 ◽  
Vol 396-398 ◽  
pp. 2012-2017
Author(s):  
Shi Zhou Du ◽  
Wen Jiang Huang ◽  
Rong Fu Wang ◽  
Ju Hua Luo ◽  
Jin Ling Zhao ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Disease Severity ◽  
Hyperspectral Data ◽  
Characteristic Parameters ◽  
Spectral Reflectivity ◽  
Wheat Powdery Mildew ◽  
Severity Levels ◽  
Wheat Leaves ◽  
The Right ◽  
Continuum Removal

The hyperspectral bands sensitive to the disease severity levels of wheat powdery mildew was elucidated in this study. The disease severity levels of wheat powdery mildew were also inverted by the extracting characteristic parameters, which provided a basis for detecting the wheat powdery mildew using hyperspectral data. The spectral data of single leaves was obtained at heading stage, the spectral characteristic parameters and sensitivity of wheat leaves were analyzed qualitatively and quantitatively. The result showed that spectral reflectivity within the visible wavebands (400—760 nm) was increased with the aggravating disease severity levels. The spectral sensitivity reached the maximum value within visible wavebands and the optimal sensitive bands for detecting disease severity levels was 630—680nm. After the spectrum was continuum removal-treated, the absorption position moved to longer wavelength with the aggravating disease severity levels and the disease severity levels showed extremely significant negative correlations with the absorption height, absorption width and absorption area. The linear regression equation has high determination coefficient and low root mean square error using the right AAI as independent variable to establish the model. Moreover, the precision verification test also showed that the model performed best in monitoring wheat powdery mildew. In conclusion, disease severity levels of wheat powdery mildew could be inverted effectively by hyperspectral technology, which provides the foundation for detecting wheat powdery mildew.

scholarly journals Detection of spring wheat plants affected by powdery mildew using hyperspectral survey data

2021 ◽  
Author(s):  
T.A. Gurova ◽  
O.A. Dubrovskaja ◽  
O.V. Elkin ◽  
L.V. Maximov ◽  
I.A. Pestunov ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Survey Data ◽  
Spring Wheat ◽  
Laboratory Experiments ◽  
Spectral Characteristics ◽  
Blumeria Graminis ◽  
Field Conditions ◽  
Wheat Leaves ◽  
Hyperspectral Camera

In laboratory experiments, spectral characteristics of three varieties of Siberian selection spring wheat affected under field conditions by powdery mildew (Blumeria graminis (DC.) Speer) were obtained using hyperspectral camera. The variety specificity of the reflectivity of wheat leaves affected by powdery mildew with the same severity has been established. A change in the leaves reflectivity depending on the severity was revealed. The most informative spectral indicator (index) for the powdery mildew detection has been determined.

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