scholarly journals Initial events in the establishment of cereal powdery mildew infection

2002 ◽  
Vol 38 (SI 1 - 6th Conf EFPP 2002) ◽  
pp. S65-S68 ◽  
Author(s):  
T.L.W. Carver ◽  
A.J. Wright ◽  
B.J. Thomas
Keyword(s):  
Powdery Mildew ◽  
Germ Tube ◽  
Blumeria Graminis ◽  
Extracellular Material ◽  
Contact Site ◽  
Powdery Mildew Fungus ◽  
Wind Speeds ◽  
Tube Emergence ◽  
Conidial Surface ◽  
Powdery Mildew Infection

Like spores of many fungi, conidia of Blumeria graminis, the powdery mildew fungus of cereals, release extracellular material. It is released within seconds where conidial surface projections touch a leaf. This ECM is probably adhesive since centrifugation showed that forces greater than those due to normal wind speeds are needed to displace conidia. Also, ECM release is probably involved in rapid sensing of substratum contact, leading to germ tube emergence close to the contact site. Thus, ECM release apparently confers at least two benefits to pathogen survival.

Early interactions during powdery mildew infection

1995 ◽  
Vol 73 (S1) ◽  
pp. 632-639 ◽  
Author(s):  
T. L. W. Carver ◽  
S. M. Ingerson-Morris ◽  
B. J. Thomas ◽  
R. J. Zeyen
Keyword(s):  
Powdery Mildew ◽  
Germ Tube ◽  
Erysiphe Graminis ◽  
External Factors ◽  
Extracellular Material ◽  
Adhesive Properties ◽  
Cell Components ◽  
Spore Deposition ◽  
Germ Tubes ◽  
Powdery Mildew Infection

Within minutes of spore deposition, enzymes including cutinase are released by conidia of Erysiphe graminis; these may prepare the infection court and facilitate subsequent fungal development. Germination follows with emergence of the primary germ tube, which contacts the host leaf. Extracellular material is secreted beneath the primary germ tube, which adheres to the leaf. The primary germ tube forms a penetration peg that breaches the host surface and gains access to host cell components including water. The primary germ tube also recognises factor(s) present in the host surface, and this stimulates elongation of the second-formed germ tube. The elongated second tube in turn responds to host surface factor(s) by differentiating an appressorium. Extracellular material, secreted beneath the growing appressorial germ tube, is laid down thickly around the appressorial lobe. An inner ring of extracellular material can often be seen surrounding penetration pores revealed by the removal of primary germ tubes and appressoria. The chemistry of the extracellular material is unknown, but in addition to adhesive properties recent studies show that a monoclonal antibody that recognises purified cutinase and, possibly, hemicellulases, binds to secretions from conidia, primary germ tubes, and appressoria. External factors can also influence germling development. Although light has little effect on the early stages of germling development, it has a profound effect in delaying the formation of haustoria by apparently mature appressoria. Understanding the control of early pathogen development could indicate avenues for genetic engineering and breeding for disease-resistant plants. Key words: Erysiphe graminis, powdery mildew, primary germ tube (PGT), appressoria, extracellular material.

scholarly journals The Ambivalence of the Barley Mlo Locus: Mutations Conferring Resistance Against Powdery Mildew (Blumeria graminis f. sp. hordei) Enhance Susceptibility to the Rice Blast Fungus Magnaporthe grisea

1999 ◽  
Vol 12 (6) ◽  
pp. 508-514 ◽  
Author(s):  
Birgit Jarosch ◽  
Karl-Heinz Kogel ◽  
Ulrich Schaffrath
Keyword(s):  
Powdery Mildew ◽  
Rice Blast ◽  
Magnaporthe Grisea ◽  
Durable Resistance ◽  
Rice Blast Fungus ◽  
Blumeria Graminis ◽  
Negative Regulator ◽  
Powdery Mildew Fungus ◽  
Mesophyll Cells ◽  
Blast Fungus

Recessive alleles of the barley Mlo locus confer non-race-specific resistance against the powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh). Recently the Mlo gene has been isolated and it was suggested that the Mlo product is a negative regulator of cell death. Thus, loss of function can precondition cells to a higher responsiveness for the onset of multiple defense functions. Here, we document an enhanced susceptibility of barley mlo mutants to the rice blast fungus Magnaporthe grisea. The disease phenotype is independent of the barley cultivar in which the mlo allele has been introgressed and occurs in equal amounts in barley backcross lines of cv. Ingrid carrying the mlo-1, mlo-3, or mlo-5 allele. Ror genes, which are required for the full expression of mlo resistance in barley against Bgh, do not affect the specific mlo-mediated phenotype observed after M. grisea infection. Formation of an effective papilla restricts blast development in epidermal cells of Mlo plants. In contrast, papillae are mostly penetrated in mlo mutants and, as a consequence, the fungus spreads into adjacent mesophyll cells. Both wild-type plants and mlo mutants did not differ in perception of a purified elicitor derived from M. grisea. Thus, we hypothesize that a functional Mlo protein is a prerequisite for penetration resistance of barley to fungal pathogens like M. grisea. The benefit of mlo alleles for durable resistance in barley and a proposed role of mlo-type-mutations in rice are discussed.

Impact of proquinazid on appressorial development of the barley powdery mildew fungus Blumeria graminis f.sp hordei

2009 ◽  
Vol 94 (2-3) ◽  
pp. 127-132 ◽  
Author(s):  
Sally R. Gilbert ◽  
Hans J. Cools ◽  
Bart A. Fraaije ◽  
Andy M. Bailey ◽  
John A. Lucas
Keyword(s):  
Powdery Mildew ◽  
Blumeria Graminis ◽  
Powdery Mildew Fungus ◽  
Barley Powdery Mildew

Cell death in wheat roots induced by the powdery mildew fungus Blumeria graminis f. sp. tritici

2009 ◽  
Vol 328 (1-2) ◽  
pp. 45-55 ◽  
Author(s):  
Xiang-Yi Deng ◽  
Ji-Wei Li ◽  
Zhu-Qing Zhou ◽  
Hai-Yan Fan
Keyword(s):  
Cell Death ◽  
Powdery Mildew ◽  
Blumeria Graminis ◽  
Powdery Mildew Fungus ◽  
Wheat Roots

scholarly journals High Humidity Causes Abnormalities in the Process of Appressorial Formation of Blumeria graminis f. sp. hordei

Pathogens ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 45
Author(s):  
Koreyuki Sugai ◽  
Hiroshi Inoue ◽  
Chie Inoue ◽  
Mayuko Sato ◽  
Mayumi Wakazaki ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Germ Tube ◽  
Penetration Rate ◽  
Blumeria Graminis ◽  
High Humidity ◽  
Appressorium Formation ◽  
Humidity Condition ◽  
Barley Powdery Mildew ◽  
Low Humidity ◽  
High Humidity Condition

High humidity decreases the penetration rate of barley powdery mildew Blumeria graminis f. sp. hordei. However, the mechanism is not well understood. In this study, the morphological and cytochemical analyses revealed that substances containing proteins leaked from the tip of the appressorial germ tube of conidia without the formation of appressorium under a high humidity condition. In addition, exposure to high humidity prior to the formation of appressorium caused the aberrant formation of the appressorial germ tube without appressorium formation, resulting in failure to penetrate the host cell. These findings suggest that the formation and maturation of the appressorium requires a low humidity condition, and will be clues to improve the disease management by humidity control.

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.

scholarly journals Estimation of winter rye (Secale cereale L.) susceptibility to infection by powdery mildew (Blumeria graminis F. sp. secalis)

2013 ◽  
Vol 66 (3) ◽  
pp. 49-54
Author(s):  
Henryk Bujak ◽  
Andrzej Jurkowski
Keyword(s):  
Powdery Mildew ◽  
Inbred Lines ◽  
Blumeria Graminis ◽  
Winter Rye ◽  
Point Scale ◽  
Crossing Experiments ◽  
Homogeneous Groups ◽  
Susceptibility To Infection ◽  
Secale Cereale L ◽  
Powdery Mildew Infection

In cold and wet years, powdery mildew (<em>Blumeria graminis</em>) causes losses in the yield of winter rye (<em>Secale cerale</em> L.) amounting to 20%. In order to control the incidence of this disease and reduce the use of fungicides, it is recommendable to grow winter rye cultivars that are resistant or tolerant to infection by <em>Blumeria</em> <em>graminis</em>. The first step in the programmes of resistance-oriented cultivation of winter rye is the choice of adequate components for crossing. Such components should be characterized by resistance to powdery mildew infection, a trait which would be passed onto the new genotypes to be obtained. The paper discusses the outcome of research aimed at selecting inbred lines of winter rye distinguishable by the lowest susceptibility to infection by <em>Blumeria graminis</em>. The evaluation covered 233 winter rye genotypes which had been inoculated with a field population of the pathogen mentioned. The level of infection was defined in a five-point scale from 0 to 4 (the authors’ own scale). Next, the results were analyzed statistically. The genotypes under study were divided using Duncan’s test into homogeneous groups. Seven such groups were distinguished. The first homogeneous group, of the lowest level of infection, comprised five inbred lines of rye. These lines can serve as components for crossing experiments in programmes of resistance-oriented breeding.

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