Ultrastructure and immunocytochemistry of the host–pathogen interface in poinsettia leaves infected with powdery mildew

2004 ◽  
Vol 82 (4) ◽  
pp. 421-429 ◽  
Author(s):  
G J Celio ◽  
C W Mims. ◽  
E A Richardson
Keyword(s):  
Powdery Mildew ◽  
Chemical Nature ◽  
Arabinogalactan Proteins ◽  
Host Cells ◽  
Euphorbia Pulcherrima ◽  
Powdery Mildew Fungus ◽  
Transmission Electron ◽  
Host Pathogen ◽  
Excellent Preservation ◽  
Extrahaustorial Matrix

Transmission electron microscopy of high-pressure frozen and freeze-substituted samples was used to examine details of the host–pathogen interface in poinsettia leaf epidermal cells infected by the powdery mildew fungus Oidium sp. Cryofixation provided excellent preservation of both host cells and fungal haustoria. Each haustorium possessed a slender neck and an expanded body with numerous slender, aseptate, coiled lobes. The extrahaustorial membrane that separated each haustorium from the cytoplasm of an invaded host cell appeared thicker than other cellular membranes and was highly convoluted, particularly near the distal end of the haustorium neck. The neck of each haustorium was encased by a papilla that formed in response to the development of a haustorium. Immunogold labeling was used to elucidate the chemical nature of these papillae. Epitopes of callose, xyloglucan, and arabinogalactan proteins were localized in three separate regions of papillae. The localization sites for these compounds in poinsettia pa pillae differed somewhat from their reported locations in papillae of various other plants infected by either true fungi or oomycetes. In the current study, no labeling with the antibodies used was observed on the extrahaustorial matrix, the extrahaustorial membrane, the fungal plasma membrane, or the host plasma membrane.Key words: Oidium sp., Euphorbia pulcherrima, host–pathogen interactions, papillae, haustoria.

Studies of the powdery-mildew fungus, Leveillula taurica, on green pepper. II. Light and electron microscopic observation of the infection process

1979 ◽  
Vol 57 (22) ◽  
pp. 2501-2508 ◽  
Author(s):  
Hitoshi Kunoh ◽  
Mitsuru Kohno ◽  
Sadayoshi Tashiro ◽  
Hiroshi Ishizaki
Keyword(s):  
Powdery Mildew ◽  
Light And Electron Microscopy ◽  
Host Cells ◽  
Outer Cell ◽  
Lipid Bodies ◽  
Powdery Mildew Fungus ◽  
Green Pepper ◽  
Ultrastructural Studies ◽  
Leveillula Taurica ◽  
Powdery Mildew Fungi

Almost all ultrastructural studies of powdery-mildew fungi have been focused on the epiparasitic fungi. In this paper, one of the endoparasitic powdery-mildew fungi, Leveillula taurica (Lev.) Arn., on green pepper (Capsicum annuum L. var. angulosum Mill.) leaves was investigated by light and electron microscopy. Most germinated conidia formed a lobed adhesion body (similar to the appressorium in morphology but different in function) before stomatal invasion. The track of the adhesion body on the leaf epidermis was depressed, and no cuticular perforations were observed in it. After stomatal invasion, infection hyphae grew extensively into the intercellular spaces of the leaves and formed haustoria in the spongy- and palisade-parenchyma cells. The haustorium was flask shaped with a neck arising from the intercellular hypha. The overall profiles of the haustorium resembled those of epiphytic powdery-mildew fungi of other authors; the haustorium was composed of a nucleate central body and many anucleate lobes, and the entire structure was bounded by an extrahaustorial membrane. Papillae consisting of three distinct regions formed against the outer cell walls at the site of penetration. The most obvious alteration in infected host cells was a marked increase in the number of large lipid bodies. Lipid bodies increased in number with time after haustorial formation. They appeared first in the host cytoplasm near the extrahaustorial membrane, then in the extrahaustorial matrix and haustorial body.

scholarly journals The isoelectric point of proteins influences their translocation to the extrahaustorial matrix of the barley powdery mildew fungus

2019 ◽  
Vol 21 (12) ◽  
Author(s):  
Lara Smigielski ◽  
Geziel B. Aguilar ◽  
Mark Kwaaitaal ◽  
Wen‐Jing Zhang ◽  
Hans Thordal‐Christensen
Keyword(s):  
Powdery Mildew ◽  
Isoelectric Point ◽  
Powdery Mildew Fungus ◽  
Barley Powdery Mildew ◽  
Extrahaustorial Matrix

Ultrastructure of the haustorium of the peanut late leaf spot fungus Cercosporidium personatum

1989 ◽  
Vol 67 (4) ◽  
pp. 1198-1202 ◽  
Author(s):  
C. W. Mims ◽  
E. S. Luttrell ◽  
S. C. Alderman
Keyword(s):  
Host Cell ◽  
Host Cells ◽  
Electron Microscopic ◽  
Cercosporidium Personatum ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Biotrophic Fungi ◽  
Leaf Spot Fungus ◽  
Extrahaustorial Matrix ◽  
Cell Protoplast

Data from scanning and transmission electron microscopic observations support light microscopic reports of the production of haustoria by the hemibiotrophic fungus Cercosporidium personatum. The trunklike base of the haustorium extended a short distance into the host cell where it formed three to five slightly thinner primary branches. These branches terminated in multiple, smaller, mostly opposite branch tips that gave the end of the haustorium a coralloid appearance. The morphology of this haustorium was distinctly different from the more extensively studied haustoria of various biotrophic fungi. Haustoria of C. personatum were observed in both living and dead host cells. In living cells an extrahaustorial matrix and extrahaustorial membrane separated the haustorium wall from the host cell protoplast. In dead cells the extrahaustorial membrane was absent. Haustoria in dead cells remained intact and appeared healthy.

scholarly journals Ecophysiological, morphological, and biochemical traits of free-living Diplosphaera chodatii (Trebouxiophyceae) reveal adaptation to harsh environmental conditions

PROTOPLASMA ◽  
2021 ◽  
Author(s):  
Cynthia Medwed ◽  
Andreas Holzinger ◽  
Stefanie Hofer ◽  
Anja Hartmann ◽  
Dirk Michalik ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Botanical Garden ◽  
Tree Bark ◽  
Photon Flux ◽  
Low Light ◽  
Transmission Electron ◽  
Light Requirements ◽  
Adaptive Mechanisms ◽  
Terrestrial Habitats ◽  
Excellent Preservation

AbstractSingle-celled green algae within the Trebouxiophyceae (Chlorophyta) are typical components of terrestrial habitats, which often exhibit harsh environmental conditions for these microorganisms. This study provides a detailed overview of the ecophysiological, biochemical, and ultrastructural traits of an alga living on tree bark. The alga was isolated from a cypress tree in the Botanical Garden of Innsbruck (Austria) and identified by morphology and molecular phylogeny as Diplosphaera chodatii. Transmission electron microscopy after high-pressure freezing (HPF) showed an excellent preservation of the ultrastructure. The cell wall was bilayered with a smooth inner layer and an outer layer of polysaccharides with a fuzzy hair-like appearance that could possibly act as cell-cell adhesion mechanism and hence as a structural precursor supporting biofilm formation together with the mucilage observed occasionally. The photosynthetic-irradiance curves of D. chodatii indicated low light requirements without photoinhibition at high photon flux densities (1580 μmol photons m−2 s−1) supported by growth rate measurements. D. chodatii showed a high desiccation tolerance, as 85% of its initial value was recovered after controlled desiccation at a relative humidity of ~10%. The alga contained the low molecular weight carbohydrates sucrose and sorbitol, which probably act as protective compounds against desiccation. In addition, a new but chemically not elucidated mycosporine-like amino acid was detected with a molecular mass of 332 g mol−1 and an absorption maximum of 324 nm. The presented data provide various traits which contribute to a better understanding of the adaptive mechanisms of D. chodatii to terrestrial habitats.

scholarly journals Disruption of barley immunity to powdery mildew by an in-frame Lys-Leu deletion in the essential protein SGT1

Genetics ◽  
2020 ◽  
Vol 217 (2) ◽  
Author(s):  
Antony V E Chapman ◽  
Matthew Hunt ◽  
Priyanka Surana ◽  
Valeria Velásquez-Zapata ◽  
Weihui Xu ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Novel Mutation ◽  
Exome Capture ◽  
Resistance Locus ◽  
Hordeum Vulgare L ◽  
Powdery Mildew Fungus ◽  
Pathogen Effectors ◽  
Cell Processes ◽  
Disease Resistances

Abstract Barley (Hordeum vulgare L.) Mla (Mildew resistance locus a) and its nucleotide-binding, leucine-rich-repeat receptor (NLR) orthologs protect many cereal crops from diseases caused by fungal pathogens. However, large segments of the Mla pathway and its mechanisms remain unknown. To further characterize the molecular interactions required for NLR-based immunity, we used fast-neutron mutagenesis to screen for plants compromised in MLA-mediated response to the powdery mildew fungus, Blumeria graminis f. sp. hordei. One variant, m11526, contained a novel mutation, designated rar3 (required for Mla6 resistance3), that abolishes race-specific resistance conditioned by the Mla6, Mla7, and Mla12 alleles, but does not compromise immunity mediated by Mla1, Mla9, Mla10, and Mla13. This is analogous to, but unique from, the differential requirement of Mla alleles for the co-chaperone Rar1 (required for Mla12 resistance1). We used bulked-segregant-exome capture and fine mapping to delineate the causal mutation to an in-frame Lys-Leu deletion within the SGS domain of SGT1 (Suppressor of G-two allele of Skp1, Sgt1ΔKL308–309), the structural region that interacts with MLA proteins. In nature, mutations to Sgt1 usually cause lethal phenotypes, but here we pinpoint a unique modification that delineates its requirement for some disease resistances, while unaffecting others as well as normal cell processes. Moreover, the data indicate that the requirement of SGT1 for resistance signaling by NLRs can be delimited to single sites on the protein. Further study could distinguish the regions by which pathogen effectors and host proteins interact with SGT1, facilitating precise editing of effector incompatible variants.

scholarly journals Powdery Mildew Fungus on Cucurbits in the Transvaal Province of South Africa

Nature ◽  
1966 ◽  
Vol 209 (5026) ◽  
pp. 938-938 ◽  
Author(s):  
G. J. M. A. GORTER
Keyword(s):  
South Africa ◽  
Powdery Mildew ◽  
Powdery Mildew Fungus

Etude ultrastructurale des relations hôte–parasite au cours de l'infection des pommes par le Phytophthora cactorum

1981 ◽  
Vol 59 (2) ◽  
pp. 251-263 ◽  
Author(s):  
X. Mourichon ◽  
G. Sallé
Keyword(s):  
Cell Walls ◽  
Susceptible Variety ◽  
Host Cells ◽  
Phytophthora Cactorum ◽  
Electron Microscopic ◽  
Susceptible Host ◽  
Golden Delicious ◽  
Extrahaustorial Matrix ◽  
Apple Fruits

An electron microscopic study was performed on haustoria of Phytophthora cactorum (L. et C.) Schroeter developed in tissues of two cultivars of apple fruits: a susceptible variety ('Golden delicious') and a resistant one ('Belle de Boskoop'). Ultrastructure of intercellular hyphae and some aspects of their penetration between contiguous host cells were described. A light dissolution of the host cell walls was observed. Ontogenic investigations indicated that in the susceptible host, the wall of the fungal haustoria was covered with a dense-stained extrahaustorial matrix. Its origin and its polysaccharide nature were demonstrated. On the other hand, the resistant host developed, immediately after the inoculation, a papilla which gave rise, later on, to a sheath enclosing adult haustoria. The role of these callosic structures in the phenomenon of resistance was discussed.

scholarly journals Erysiphe trifolii Causing Powdery Mildew of Lentil (Lens culinaris)

Plant Disease ◽  
2009 ◽  
Vol 93 (8) ◽  
pp. 797-803 ◽  
Author(s):  
Renuka N. Attanayake ◽  
Dean A. Glawe ◽  
Frank M. Dugan ◽  
Weidong Chen
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
The United States ◽  
Morphological Characters ◽  
Grain Legumes ◽  
Its Sequences ◽  
Powdery Mildew Fungus ◽  
The Pacific ◽  
Soybean Genotypes ◽  
Erysiphe Trifolii

The taxonomy of the powdery mildew fungus infecting lentil in the Pacific Northwest (PNW) of the United States was investigated on the basis of morphology and rDNA internal transcribed spacer (ITS) sequences. Anamorphic characters were in close agreement with descriptions of Erysiphe trifolii. However, teleomorphs formed chasmothecial appendages with highly branched apices, whereas E. trifolii has been described as producing flexuous or sometimes loosely branched appendages. Branched appendages have been described in Erysiphe diffusa, a fungus reported from species of Lens, Glycine, and Sophora, raising the possibility that the PNW fungus could be E. diffusa. Examination of morphological characters of an authentic specimen of E. trifolii from Austria determined that it included chasmothecial appendages resembling those seen in PNW specimens. Furthermore, ITS sequences from five powdery mildew samples collected from lentils in PNW greenhouses and fields from 2006 to 2008 were identical to one another, and exhibited higher similarity to sequences of E. trifolii (99%) than to those of any other Erysiphe spp. available in GenBank. Parsimony analysis grouped the lentil powdery mildew into a clade with Erysiphe baeumleri, E. trifolii, and E. trifolii–like Oidium sp., but indicated a more distant relationship to E. diffusa. In greenhouse inoculation studies, the lentil powdery mildew fungus did not infect soybean genotypes known to be susceptible to E. diffusa. The pathogenicity of E. trifolii on lentil was confirmed using modified Koch's postulates. This is the first report of E. trifolii infecting lentil. E. diffusa and E. trifolii have different host ranges, so the discovery of E. trifolii on lentil has implications both for determining species of powdery mildews on cool-season grain legumes, and in disease management.

Antifungal Effectiveness of Nanosilver Colloid against Rose Powdery Mildew in Greenhouses

2008 ◽  
Vol 135 ◽  
pp. 15-18 ◽  
Author(s):  
Hae Sic Kim ◽  
Hyun Suk Kang ◽  
Gyo Jin Chu ◽  
Hong Sik Byun
Keyword(s):  
Electron Microscopy ◽  
Powdery Mildew ◽  
Colloidal Solution ◽  
Physical Method ◽  
Average Diameter ◽  
Optical Microscope ◽  
Size Analysis ◽  
Large Area ◽  
Transmission Electron ◽  
Antifungal Effects

The antifungal effectiveness against rose powdery mildew using antimicrobial nanosilver colloidal solution was investigated. Double-capsulized nanosilver was prepared by chemical reaction of silver ion with aid of physical method, reducing agent and stabilizers. The average diameter of nanosilver was about 1.5 nm. They were highly stable and very well dispersive in aqueous solution. The Transmission electron microscopy and UV-vis spectrometer were used for measurements of size analysis and their stability, respectively. The nanosilver colloidal solution of concentration of 5000 ppm was diluted in 10 ppm of 500 kg and sprayed at large area of 3306 m2polluted by rose powdery mildew. The white rose powdery mildew fade out above 95 % after 2 days and was not recurred for a week. The antifungal effects were observed by an optical microscope and photographs.

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