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.

Structure and host–actinomycete interactions in developing root nodules of Comptonia peregrina

1978 ◽  
Vol 56 (5) ◽  
pp. 502-531 ◽  
Author(s):  
William Newcomb ◽  
R. L. Peterson ◽  
Dale Callaham ◽  
John G. Torrey
Keyword(s):  
Host Cell ◽  
Root Nodules ◽  
Host Cells ◽  
Electron Microscopic ◽  
Cortical Cells ◽  
Host Cytoplasm ◽  
Transmission Electron ◽  
Microscopic Studies ◽  
Host Plasma Membrane ◽  
Soil Actinomycete

Correlated fluorescence, bright-field, transmission electron, and scanning electron microscopic studies were made on developing root nodules of Comptonia peregrina (L.) Coult. (Myricaceae) produced by a soil actinomycete which invades the root and establishes a symbiosis leading to fixation of atmospheric dinitrogen. After entering the host via a root hair infection, the hyphae of the endophyte perforate root cortical cells by local degradation of host cell walls and penetration of the host cytoplasm. The intracellular hyphae are always surrounded by host plasma membrane and a thick polysaccharide material termed the capsule. (For convenience, term intracellular refers to the endophyte being inside a Comptonia cell as distinguished from being intercellular, i.e.. between host cells, even though the former is actually extracellular as the endophyte is separated from the host cytoplasm by the host plasmalemma.) Numerous profiles of vesiculate rough endoplasmic reticulum (RER) occur near the growing hyphae. Although the capsule shows a positive Thiery reaction indicating its polysaccharide nature, the fibrillar contents of the RER do not, leaving uncertain whether the capsule results from polymers derived from the RER. Amyloplasts of the cortical cells lose their starch deposits during hyphal proliferation. The hyphae branch extensively in specific layers of the cortex, penetrating much of the host cytoplasm. At this stage, hyphal ends become swollen and form septate club-shaped vesicles within the periphery of the host cells. Lipid-like inclusions and Thiery-positive particles, possibly glycogen, are observed in the hyphae at this time. Associated with hyphal development is an increase in average host cell volume, although nuclear volume appears to remain constant. Concomitant with vesicle maturation, the mitochondrial population increases sharply, suggesting a possible relationship to vesicle function. The intimate interactions between host and endophyte during development of the symbiotic relationship are emphasized throughout.

scholarly journals Identification of a Chlorovirus PBCV-1 Protein Involved in Degrading the Host Cell Wall during Virus Infection

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 782
Author(s):  
Irina V. Agarkova ◽  
Leslie C. Lane ◽  
David D. Dunigan ◽  
Cristian F. Quispe ◽  
Garry A. Duncan ◽  
...  
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Cell Walls ◽  
Virus Entry ◽  
Cell Type ◽  
Chlorella Variabilis ◽  
Rigid Cell Wall ◽  
Host Cell Wall ◽  
Cell Type Specific ◽  
Eukaryotic Organisms

Chloroviruses are unusual among viruses infecting eukaryotic organisms in that they must, like bacteriophages, penetrate a rigid cell wall to initiate infection. Chlorovirus PBCV-1 infects its host, Chlorella variabilis NC64A by specifically binding to and degrading the cell wall of the host at the point of contact by a virus-packaged enzyme(s). However, PBCV-1 does not use any of the five previously characterized virus-encoded polysaccharide degrading enzymes to digest the Chlorella host cell wall during virus entry because none of the enzymes are packaged in the virion. A search for another PBCV-1-encoded and virion-associated protein identified protein A561L. The fourth domain of A561L is a 242 amino acid C-terminal domain, named A561LD4, with cell wall degrading activity. An A561LD4 homolog was present in all 52 genomically sequenced chloroviruses, infecting four different algal hosts. A561LD4 degraded the cell walls of all four chlorovirus hosts, as well as several non-host Chlorella spp. Thus, A561LD4 was not cell-type specific. Finally, we discovered that exposure of highly purified PBCV-1 virions to A561LD4 increased the specific infectivity of PBCV-1 from about 25–30% of the particles forming plaques to almost 50%. We attribute this increase to removal of residual host receptor that attached to newly replicated viruses in the cell lysates.

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.

An electron microscope study of the intracellular hyphae of some smut fungi (Ustilaginales)

1970 ◽  
Vol 18 (3) ◽  
pp. 285 ◽  
Author(s):  
RA Fullerton
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Host Cell ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Smut Fungi ◽  
Sheath Formation ◽  
Host Cell Wall ◽  
Similar Appearance ◽  
Host Tissues

A number of species of systemic smut fungi have been examined. Hyphae occupy inter- and intracellular positions in the host tissues. Intracellular hyphae resemble haustoria in many respects. Host plasmalemmae are invaginated by invading hyphae, and encapsulations are formed. Material of similar appearance to the host cell wall is deposited within encapsulations and many hyphae are eventually completely ensheathed. A possible mechanism for sheath formation is suggested.

Host – parasite relationships between the fungus Leptosphaerulina crassiasca and peanut

1992 ◽  
Vol 70 (9) ◽  
pp. 1724-1733 ◽  
Author(s):  
Mei-Lee Wu ◽  
Richard T. Hanlin
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Germ Tube ◽  
Light And Electron Microscopy ◽  
Host Cells ◽  
Detached Leaves ◽  
Host Cell Wall ◽  
Host Parasite ◽  
Germ Tubes ◽  
Infection Hypha

The mode of penetration and infection of the peanut leaf by Leptosphaerulina crassiasca were studied by means of light and electron microscopy. The attachment of the multicellular ascospores to the leaf surface was by a mucilagenous sheath that covered the ascospores at maturity. This sheath expanded rapidly in moisture and it extended along the germ tube as it elongated. Two types of germ tubes appeared to be formed, a short one and a relatively long one. Short germ tubes were not delimited by septa, and they penetrated the cuticle and host epidermal cell wall directly without appressorium formation. Penetration occurred 2–6 h after inoculation. The wall was breached by a relatively broad infection hypha that expanded in width inside the host cell wall. The lack of mechanical rupture at the infection site indicated that penetration may involve enzymatic activity. Intracellular hyphae were present in the epidermal cells, but only intercellular hyphae occurred in the palisade and spongy mesophyll tissues. The intercellular hyphae were frequently appressed to the outer surface of the host cell wall. Infected areas rarely exceeded 1 mm in diameter, and they were only sparsely colonized by hyphae of the pathogen. Host cells in the vicinity of hyphae underwent senescence and death. One to 2 months after inoculation, pseudothecia formed in the dead tissues of detached leaves. In some instances the presence of penetration hyphae by short germ tubes induced the formation of a papilla inside the host cell wall, which either restricted growth of the infection hypha or resulted in the death of the germ tube and the cell from which it arose. Long germ tubes were delimited by simple septa and they terminated in an appressorium; however, details of their behavior were not studied. Key words: Arachis hypogaea, Ascomycotina, Dothideales, leaf scorch, pepper spot.

Development of haustoria of Melampsora lini

1972 ◽  
Vol 50 (8) ◽  
pp. 1701-1703 ◽  
Author(s):  
Larry J. Littlefield
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Initial Step ◽  
The Body ◽  
Stages Of Development ◽  
Melampsora Lini ◽  
Host Cell Wall ◽  
Dark Staining ◽  
Thickened Wall ◽  
Mycelial Cell

An initial step in haustorium formation is the contact of a terminal intercellular mycelial cell with the wall of a host cell. The former differentiates to form a haustorial mother cell having a thickened wall in the region of contact. A penetration peg develops in the thickened region of the cell wall; it elongates, penetrates the host cell wall, and extends into the lumen of the host cell. A dark-staining region, the neck ring, develops in the wall of the penetration peg and persists throughout subsequent stages of development. The distal end of the penetration peg expands to form a somewhat spherical haustorial body. Subsequently, one to several lobes form on, and extend from, the body of the haustorium. The more ephemeral stages of development are the initiation of the spherical haustorial body and the elongation of the penetration peg. The less ephemeral stages are prepenetration and early postpenetration of the host cell wall and the intermediate stages of haustorial expansion.

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.

The Alternaria brassicae – Nectria inventa host–parasite interface

1977 ◽  
Vol 55 (4) ◽  
pp. 448-454 ◽  
Author(s):  
A. Tsuneda ◽  
W. P. Skoropad
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Host Cells ◽  
Alternaria Brassicae ◽  
Adhesive Material ◽  
Large Hole ◽  
Mature Conidium ◽  
Host Cell Wall ◽  
Host Parasite

The Verticillium state of Nectria inventa is a destructive parasite of Alternaria brassicae. Tropic growth of parasite hyphae towards hyphae and conidia of A. brassicae occurs in the vicinity of the host. Upon contact, the parasite hyphae often form appressorium-like bodies on the host cells and produce fibrous adhesive material at the host–parasite interface. Conidia are penetrated more commonly than hyphae. Penetration of the septa in hyphae results in a separation of cells. Penetration of a mature conidium also occurs commonly at a septum. The presence of a large hole in the wall of the host cell and the meshwork of material at the penetration site suggest that enzymatic breakdown of host cell wall occurs. Juvenile conidia are penetrated usually at the basal pore.

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