Changes of plasmolysis form in epidermal cells of Hordeum vulgare infected by Erysiphe graminis: evidence for increased membrane–wall adhesion

1984 ◽  
Vol 62 (8) ◽  
pp. 1714-1723 ◽  
Author(s):  
O. Y. Lee-Stadelmann ◽  
W. R. Bushnell ◽  
E. J. Stadelmann
Keyword(s):  
Cell Wall ◽  
Hordeum Vulgare ◽  
Host Cell ◽  
Cell Walls ◽  
Membrane Structure ◽  
Epidermal Cells ◽  
Erysiphe Graminis ◽  
Infected Tissue ◽  
Host Cells

When coleoptile epidermal tissues of Hordeum vulgare were plasmolyzed with α-methylglucose or mannitol, 24–72 h after inoculation with Erysiphe graminis f. sp. hordei, host protoplasts tended to pull away from one or more sites on longitudinal host cell walls producing a concave pocket at each site. This contrasted with the usual convex form of plasmolysis in uninfected tissue in which protoplasts pulled from the short transversal end walls of host cells forming protoplasts with convex ends. The tendency for concave plasmolysis encompassed entire inoculated areas at 5 colonies/mm2 and above. The concave response occurred in coleoptiles inoculated 7–12 days after planting, but not in ones inoculated at 5 days. It occurred in four of five barley lines tested at 48 h postinoculation. Treatment before plasmolysis with 10 mM Ca2+ promoted the disease-induced concavities; treatment with 15 mM K+ partially inhibited them. The concave form in plasmolyzed infected tissue was changed to the convex form by addition of 250 μM octylguanidine to the plasmolyticum or by replacement of α-methylglucose with isosmolar urea or methyl urea solutions. The results suggest that Erysiphe graminis infection increased adhesion of the host plasmalemma to the cell wall, probably as a consequence of change in membrane structure and bridging by Ca2+ ions.

Axenic culture of flax rust isolated from cotyledons by cell-wall digestion

1972 ◽  
Vol 50 (12) ◽  
pp. 2601-2603 ◽  
Author(s):  
W. David Lane ◽  
Michael Shaw
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Cell Walls ◽  
Hydrolytic Enzymes ◽  
Axenic Culture ◽  
Rust Fungi ◽  
Host Cells ◽  
Melampsora Lini ◽  
Large Numbers ◽  
Axenic Cultures

A technique is described for the isolation of colonies of flax rust (Melampsora lini (Ehrenb.) Lév., Race No. 3) from infected cotyledons. The technique depends on the digestion of the host cell walls with hydrolytic enzymes and washing of the liberated colonies. It is thus possible to collect large numbers of flax-rust colonies with only a few host cells adhering to them. Axenic cultures were established from colonies isolated in this way. This technique may be useful in establishing axenic cultures of other rust fungi.

scholarly journals Histology of Infection of Hydrilla verticillata by Macrophomina phaseolina

Weed Science ◽  
1992 ◽  
Vol 40 (2) ◽  
pp. 288-295 ◽  
Author(s):  
Gary F. Joye ◽  
Rex N. Paul
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Hydrilla Verticillata ◽  
Macrophomina Phaseolina ◽  
Host Cells ◽  
Outer Cell ◽  
Cell Wall Disruption ◽  
Outer Cell Wall

Infection of Hydrilla verticillata by Macrophomina phaseolina was investigated using scanning and transmission electron microscopy. Sprigs of plants in petri plates were inoculated with suspensions of fungal hyphae. Samples of inoculated and noninoculated plants were taken over time. Fungal cells attached to lower epidermal cell walls but not the upper epidermal cell walls of leaves. In less than 40 h, penetration through the cell wall was completed and colonization of host cells was observed. Penetration of upper epidermis was limited to the cell wall adjacent to a lower epidermal cell. No penetration was observed through the outer cell wall of upper epidermis. Inhibition of penetration through the outer cell wall of the upper epidermis may be attributable to an osmiophilic layer below the cell wall. Disruption of the host cell walls and subsequent host cell death was preceded by massive colonization of the host by this pathogen.

Studies on the haustorium of Castilleja (Scrophulariaceae). II. The endophyte

1973 ◽  
Vol 51 (5) ◽  
pp. 923-931 ◽  
Author(s):  
David R. Dobbins ◽  
Job Kuijt
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Light Microscope ◽  
Cell Walls ◽  
Host Cells ◽  
Electron Microscopic ◽  
Cortical Cells ◽  
Host Cell Wall ◽  
Dark Staining ◽  
Host Tissues

The portion of the Castilleja haustorium within the host, the endophyte, was examined at the light-and electron-microscopic levels. The endophyte consists of a stalk of lipid-containing cells and digitate cells at its tip. Vessels run the length of the endophyte. There is a harmonious meshing between host cortical cells and those of the endophyte flank, suggesting that penetration is accomplished, in part, by cell dissolution. Crushing of cells also occurs during endophyte invasion as host phloem tissues are severely buckled and cell walls are greatly folded. Some features of digitate cells include dense cytoplasm, an abundance of endoplasmic reticulum, lateral walls that are thickened as well as those on the side adjacent to the host, and an ability to conform to the contours of host tissues. Often digitate cells are divided by very thin walls that are hardly visible under the light microscope. It is suggested that the thick cell walls may function as "free space" in the absorption of materials from the host. Within the endophyte, vessels differentiate and may contain either a finely granular, dark-staining material or a more coarsely granular, light-staining material. The particles of the latter have irregular shapes. Although granular materials are thus carried by some vessels, cells resembling the structurally intermediate "phloeotracheids" were not seen. Connections through the cell wall were not observed between parasite and host; however, within the endophyte plasmodesmata were highly branched and often contained median nodules. Transfer-like cells which have irregularly thickened walls occurred in the endophyte. Host tissues next to digitate cells appeared to be in a degraded state. Invaginations of the plasmalemma were common and small flattened vesicles were formed in some host cells from the disrupted tonoplast. In several instances, the cytoplasm had receded from the host cell wall and a "beaded" material was present in both vacuoles and large vesicles. The host cell wall at times had a very loose fibrillar appearance. Some host tracheids were occluded with a dense and dark-staining material. The xylem strands of the parasite are connected to the host xylem either by cell wall dissolution or by actual penetration of a digitate cell into a host xylary cell. The penetrating cell subsequently differentiates into a vessel member. A summary and general discussion are given to relate the two portions of the haustorium, the upper haustorium and the endophyte. The mass of new information gained in this study leads us to encourage the application of plastic embedding and sectioning techniques to further light-microscope studies on haustoria.

scholarly journals Extracellular Polysaccharides from Xanthomonas axonopodis pv. manihotis Interact with Cassava Cell Walls During Pathogenesis

1997 ◽  
Vol 10 (7) ◽  
pp. 803-811 ◽  
Author(s):  
B. Boher ◽  
M. Nicole ◽  
M. Potin ◽  
J. P. Geiger
Keyword(s):  
Cell Wall ◽  
Monoclonal Antibodies ◽  
Host Cell ◽  
Cell Walls ◽  
Plant Cell Wall ◽  
Infection Process ◽  
Extracellular Polysaccharides ◽  
Xanthomonas Axonopodis ◽  
Cassava Leaves ◽  
Host Cell Wall

The location of lipopolysaccharides produced by Xanthomonas axonopodis pv. manihotis during pathogenesis on cassava (Manihot esculenta) was determined by fluorescence and electron microscopy immunolabeling with monoclonal antibodies. During the early stages of infection, pathogen lipopolysaccharides were detected on the outer surface of the bacterial envelope and in areas of the plant middle lamellae in the vicinity of the pathogen. Later in the infection process, lipopolysaccharide-specific antibodies bound to areas where the plant cell wall was heavily degraded. Lipopolysaccharides were not detected in the fibrillar matrix filling intercellular spaces of infected cassava leaves. Monoclonal antibodies specific for the exopolysaccharide xanthan side chain labeled the bacteria, the fibrillar matrix, and portions of the host cell wall. The association of Xanthomonas lipopolysaccharides with host cell walls during plant infection is consistent with a role of these bacterial extracellular polysaccharides in the infection process.

Ultrastructure of compatible and incompatible reactions of sunflower to Plasmopara halstedii

1979 ◽  
Vol 57 (4) ◽  
pp. 315-323 ◽  
Author(s):  
Glenn Wehtje ◽  
Larry J. Littlefield ◽  
David E. Zimmer
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Host Cell ◽  
Epidermal Cell ◽  
Cortical Cell ◽  
Hypersensitive Reaction ◽  
Host Cells ◽  
Plasmopara Halstedii ◽  
Host Cell Wall ◽  
Host Plasma Membrane

Penetration of sunflower, Heliantluis animus, root epidermal cells by zoospores of Plasmopara halstedii is preceded by formation of a papilla on the inner surface of the host cell wall that invaginates the host plasma membrane. Localized degradation and penetration of the host cell wall by the pathogen follow. The invading fungus forms an allantoid primary infection vesicle in the penetrated epidermal cell. The host plasma membrane invaginates around the infection vesicle but its continuity is difficult to follow. Upon exit from the epidermal cell the fungus may grow intercellularly, producing terminal haustorial branches which extend into adjacent host cells. The fungus may grow through one or two cortical cell is after growing from the epidermal cell before it becomes intercellular. Host plasma membrane is not penetrated by haustoria. Intercellular hyphae grow toward the apex of the plant and ramify the seedling tissue. Resistance in an immune cultivar is hypersensitive and is triggered upon contact of the host cell with the encysting zoospore before the host cell wall is penetrated. Degeneration of zoospore cytoplasm accompanies the hypersensitive reaction of the host. Zoospores were often parasitized by bacteria and did not germinate unless penicillin and streptomycin were added to the inoculum suspension.

scholarly journals Ultrastructure of the Infection of Sorghum bicolor by Colletotrichum sublineolum

2001 ◽  
Vol 91 (2) ◽  
pp. 149-158 ◽  
Author(s):  
P. S. Wharton ◽  
A. M. Julian ◽  
R. J. O'Connell
Keyword(s):  
Cell Wall ◽  
Sorghum Bicolor ◽  
Epidermal Cells ◽  
Host Cells ◽  
Wall Thickening ◽  
Fungal Cell ◽  
Resistant Cultivars ◽  
Ultrastructural Studies ◽  
Opaque Material ◽  
Colletotrichum Sublineolum

Ultrastructural studies of the infection of susceptible and resistant cultivars of Sorghum bicolor by Colletotrichum sublineolum were conducted. Initial penetration events were the same on both susceptible and resistant cultivars. Germ tubes originating from germinated conidia formed globose, melanized appressoria, that penetrated host epidermal cells directly. Appressoria did not produce appressorial cones, but each penetration pore was surrounded by an annular wall thickening. Inward deformation of the cuticle and localized changes in staining properties of the host cell wall around the infection peg suggests that penetration involves both mechanical force and enzymic dissolution. In compatible interactions, penetration was followed by formation of biotrophic globular infection vesicles in epidermal cells. Filamentous primary hyphae developed from the vesicles and went on to colonize many other host cells as an intracellular mycelium. Host cells initially survived penetration. The host plasma membrane invaginated around infection vesicles and primary hyphae and was appressed tightly to the fungal cell wall, with no detectable matrix layer at the interface. Necrotrophic secondary hyphae appeared after 66 h and ramified through host tissue both intercellularly and intracellularly, forming hypostromatic acervuli by 114 h. Production of secondary hyphae was accompanied by the appearance of electron-opaque material within infected cells. This was thought to represent the host phytoalexin response. In incompatible interactions, infection vesicles and primary hyphae were formed in epidermal cells by 42 h. However, they were encrusted with electron-opaque material and appeared dead. These observations are discussed in relation to the infection processes of other Colletotrichum spp. and the host phytoalexin response.

Structure and function of wall appositions. 1. General histochemistry of papillae in barley coleoptiles attacked by Erysiphe graminis f. sp. hordei

1986 ◽  
Vol 64 (4) ◽  
pp. 793-801 ◽  
Author(s):  
Michael G. Smart ◽  
James R. Aist ◽  
Herbert W. Israel
Keyword(s):  
Cell Wall ◽  
Chemical Composition ◽  
Cell Walls ◽  
Structure And Function ◽  
Erysiphe Graminis ◽  
Wall Appositions ◽  
And Function

Penetration pegs of Erysiphe graminis D.C. f. sp. hordei Em. Marchal are usually not impeded by normal papillae of barley coleoptiles, whereas oversize papillae are impenetrable to appressoria of the pathogen. We investigated the chemical composition of these papillae and the cell walls by classical histochemistry, in part to extend the fragmented knowledge of these structures and in part to find out if there are differences between normal and oversize papillae which would account for their different efficacies in resisting penetration. These papillae were indistinguishable from one another histochemically and contained protein, carbohydrate other than pectin, and a phenolic which was not lignin. We report also a definitive proof of callose in papillae. They do not contain cutin or suberin. The cell wall did not contain callose or cutin–suberin but did contain protein, pectin, and a phenolic (also not lignin). The results imply that different linkages between molecules in oversize papillae, or some other differences not revealed in this study, are responsible for their ability to prevent fungal penetration.

LIVING HAUSTORIA AND HYPHAE OF ERYSIPHE GRAMINIS F.SP. HORDEI WITH INTACT AND PARTLY DISSECTED HOST CELLS OF HORDEUM VULGARE

1967 ◽  
Vol 45 (9) ◽  
pp. 1719-1732 ◽  
Author(s):  
W. R. Bushnell ◽  
J. Dueck ◽  
J. B. Rowell
Keyword(s):  
Hordeum Vulgare ◽  
Microbial Contamination ◽  
Hyphal Growth ◽  
Neutral Red ◽  
Parasite Growth ◽  
Erysiphe Graminis ◽  
The Body ◽  
Host Cells ◽  
Ambient Media ◽  
Hordeum Vulgare L

Erysiphe graminis DC f.sp. hordei Em. Marchal was grown on the inner epidermis of the coleoptile of barley (Hordeum vulgare L.) in mounts that permitted microscopic observation and treatment of living cells of both host and parasite. Growth rates of the mildew fungus on partially isolated single layers of epidermis from coleoptiles equaled rates on intact green leaves 48–72 h after inoculation when the colonies elongated by 14–17 μ/h. The colonies often grew at approximately normal rates for 3–6 h after the protoplasts of parasitized host cells were destroyed by dissection, with the single haustorium of the colony exposed to artificial ambient media. The most prolonged growth occurred when the contents of the host cell were replaced with solutions that were hypertonic with respect to the host (0.5–0.6 M sucrose). Haustoria in contact with hypertonic media were normal in uptake of neutral red, in apparent turgidity, and in the position of the haustorial sac closely affixed to the body of the haustorium. Removal of this single haustorium stopped hyphal growth immediately, but growth often resumed after 3–24 h and then continued for 5–24 h at rates [Formula: see text] to [Formula: see text] of the normal rate without formation of new haustoria. Microbial contamination prevented the assessment of the capabilities of mildew hyphae for growth over long periods after dissection of host cells. The results suggest, however, that haustoria exposed by the present techniques are functional and therefore might be used to investigate the nature of uptake and secretion by these structures, but that the haustorium is not essential for short periods of hyphal growth by E. graminis f.sp. hordei.

scholarly journals ANATOMY OF CHLOROTHALONIL-INDUCED GRAPE BERRY RUSSET

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 762B-762
Author(s):  
Martin C. Goffinet ◽  
Roger C. Pearson
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Grape Berry ◽  
Epidermal Cells ◽  
Daughter Cells ◽  
Vitis Labruscana ◽  
Original Cell

Clusters of Vitis labruscana cv. Concord were grown either in full sun or canopy shade, and either not sprayed or sprayed with 3.4 Kg/Ha chlorothalonil every 2 wk from pre-bloom to veraison. Only sun-exposed, sprayed fruit produced skin russeting. Clusters of the very susceptible V. vinifera cv. Rosette were grown in direct sun, sprayed with chlorothalonil 4 times from bloom to veraison, in the presence or absence of purported anti-russeting agents. Heavy russet occurred in all treatments. Russet initiation was similar in the 2 cvs.: epidermal cells first died beneath spray residue in full sun, a phellogen then arose in the hypodermis, followed by periderm. Epidermal death began in `Rosette' within a wk of the bloom spray, but in `Concord' only after 2-3 wk post bloom and 3 sprays. `Concord' russet generally appeared as patches or scabs, whereas `Rosette' russet ranged from freckles, welts, scabs to large smooth burnished areas. In both cvs., unbroken russet consisted of uniform layers of phellum. New, deeper periderm initials arose beneath checks and cracks which formed as fruit enlarged. In `Concord', but not `Rosette', the daughter cells of each such initial were often enclosed in the original cell wall. In all cases of russet, cell walls in the periderm were suberized and sometimes lignified. Cells also contained much phenolic material.

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