Ultrastructure of the interaction between Pyrenophora teres and a susceptible barley host

1979 ◽  
Vol 57 (1) ◽  
pp. 40-47 ◽  
Author(s):  
L. Van Caeseele ◽  
J. Grumbles
Keyword(s):  
Epidermal Cell ◽  
Light And Electron Microscopy ◽  
Leaf Tissue ◽  
Pyrenophora Teres ◽  
Barley Cultivar ◽  
Mesophyll Cells ◽  
Initial Penetration ◽  
Cell Layers ◽  
Epidermal Cell Wall ◽  
Host Parasite

Host–-parasite interfaces in leaves of a susceptible barley cultivar inoculated with Pyrenophora teres were studied using light and electron microscopy. Entry into the host rarely occurred through stomata, normal entry was by penetration into epidermal cells. Disruption of cell contents was evident in all initial penetration sites. After penetrating the epidermal cell, the fungus produced a large infection vesicle which gave rise to one or sometimes two intracellular hyphae. Hyphae spread down through the leaf tissue intracellularly for one or two cell layers and intercellularly thereafter. A septum, coincident with the external epidermal cell wall, was present in the infection peg located between the appressorium and the vesicle. Prior to leaving the epidermal cell, hyphae swelled to produce appressorium-like structures. These hyphae were sometimes septate at the point of exit. At sites where the infection had penetrated only four or five cell layers deep, the cellular contents of the mesophyll cells were relatively unaffected despite the presence of intercellular hyphae. However, when hyphae occasionally penetrated a host cell, gross disruption of their contents was apparent.

The ultrastructure of the Spilocaea state of Venturia inaequalis in vivo

1976 ◽  
Vol 22 (8) ◽  
pp. 1144-1152 ◽  
Author(s):  
Michael Corlett ◽  
James Chong ◽  
E. G. Kokko
Keyword(s):  
Cell Wall ◽  
Epidermal Cell ◽  
Venturia Inaequalis ◽  
Conidiogenous Cell ◽  
Epidermal Cells ◽  
Apical Region ◽  
Mesophyll Cells ◽  
Epidermal Cell Wall ◽  
Primary Conidium

There are indications that the fungus enzymatically degrades the cuticle and epidermal cell wall. The epidermal cells and to a lesser degree the palisade mesophyll cells beneath a sporulating lesion (susceptible reaction) are killed or seriously disrupted. Various stages of conidiogenesis, including development of the primary conidium, were observed. A conidium is delimited by a two-layered transverse septum. Before conidium secession, a new two-layered inner wall is laid down around the entire conidiogenous cell adjacent to the plasmalemma. The apical region of the new inner wall proliferates beyond the annellation scar left by the seceded conidium and eventually produces another conidium.

Light and electron microscopy of the spermogonial stage of Gymnoconia peckiana, one of the causes of orange rust of Rubus

Botany ◽  
2008 ◽  
Vol 86 (5) ◽  
pp. 533-538 ◽  
Author(s):  
Charles W. Mims ◽  
Elizabeth A. Richardson
Keyword(s):  
Cell Wall ◽  
Epidermal Cell ◽  
Leaf Surface ◽  
Light And Electron Microscopy ◽  
Epidermal Cells ◽  
Wall Material ◽  
Cell Wall Material ◽  
Leaf Epidermis ◽  
Single Nucleus ◽  
Epidermal Cell Wall

Hyphae of Gymnoconia peckiana (Howe in Peck) Trotter spread from infected Rubus argutus Link. stems into leaf primordia where they proliferated in an intercellular fashion as leaves differentiated. Hyphae were septate, and each compartment appeared to contain a single nucleus. Hyphae gave rise to numerous haustoria that resembled the monokaryotic haustoria of other rust fungi. Hyphae located immediately adjacent to the upper and lower leaf epidermis gave rise to spermogonial initials. Each initial consisted of a small group of tightly packed hyphae that developed in an intercellular space adjacent to the epidermis. As an initial enlarged, the proliferating hyphae pushed their way between, as well as into, epidermal cells. Invaded epidermal cells soon died. A layer of spermatiophores then developed within each young spermogonium and appeared to push the epidermal cell wall material and leaf cuticle covering the spermogonium out from the leaf surface. Once mature, spermatiophores gave rise to a succession of uninucleate spermatia that emerged from the tip of each spermatiophore. Spermatia initially accumulated beneath the layer of epidermal cell wall material and cuticle that covered the developing spermogonium and appeared to push this layer further out from the leaf surface until it ruptured. A few receptive hyphae were observed in mature spermogonia.

Host–parasite interfaces in a resistant and a susceptible cultivar of Solanum tuberosum inoculated with Phytophthora infestans: leaf tissue

1976 ◽  
Vol 54 (16) ◽  
pp. 1956-1970 ◽  
Author(s):  
Hans R. Hohl ◽  
Elisabeth Suter
Keyword(s):  
Phytophthora Infestans ◽  
Light And Electron Microscopy ◽  
Potato Cultivar ◽  
Leaf Tissue ◽  
Tissue Level ◽  
Fungal Hypha ◽  
Susceptible Cultivar ◽  
Susceptible Host ◽  
Focus Of Infection ◽  
Host Parasite

Host–parasite interfaces in leaves from a resistant (Eba) and a susceptible (Bintje) potato cultivar inoculated with Phytophthora infestans were studied using light and electron microscopy. Host penetration occurs similarly in both cultivars either through stomata or directly through the epidermis. In the susceptible host the fungus spreads throughout the tissue intercellularly and transcellularly, whereas in the resistant host it remains confined to the focus of infection. Yet in both cases live, normal-appearing hyphae can be observed even after 5 days. The appearance of haustoria in both cultivars is similar: they are either surrounded by an extrahaustorial matrix alone or in combination with wall appositions (collars or encasements). Structures with cytological features between those of haustoria and transcellular hyphae were also recorded, indicating a variety of host–parasite interactions within leaf tissue. Sporulation has been observed on the susceptible cultivar but not on the resistant one. The results suggest that cellular reactions against the intruding fungal hypha are qualitatively similar in both cultivars but that at the tissue level the intercellular spread of the pathogen and its sporulation are prevented in the resistant host but not in the susceptible host.

Ultrastructure and Senescence in an Achloroplastic Mutant of Hordeum vulgare L. cv. Dyan

1992 ◽  
Vol 50 (1) ◽  
pp. 844-845
Author(s):  
R.H.M. Cross ◽  
C.E.J. Botha ◽  
A.K. Cowan ◽  
B.J. Hartley
Keyword(s):  
Cell Wall ◽  
Hordeum Vulgare ◽  
Leaf Tissue ◽  
Ultrastructural Changes ◽  
Hordeum Vulgare L ◽  
Mesophyll Cells ◽  
Lethal Mutant ◽  
Cytoplasmic Matrix ◽  
Close Proximity ◽  
Pinocytotic Vesicles

Senescence is an ordered degenerative process leading to death of individual cells, organs and organisms. The detection of a conditional lethal mutant (achloroplastic) of Hordeum vulgare has enabled us to investigate ultrastructural changes occurring in leaf tissue during foliar senescence.Examination of the tonoplast structure in six and 14 day-old mutant tissue revealed a progressive degeneration and disappearance of the membrane, apparently starting by day six in the vicinity of the mitochondria associated with the degenerating proplastid (Fig. 1.) where neither of the plastid membrane leaflets is evident (arrows, Fig. 1.). At this stage there was evidence that the mitochondrial membranes were undergoing retrogressive changes, coupled with disorganization of cristae (Fig. 2.). Proplastids (P) lack definitive prolamellar bodies. The cytoplasmic matrix is largely agranular, with few endoplasmic reticulum (ER) cisternae or polyribosomal aggregates. Interestingly, large numbers of actively-budding dictysomes, associated with pinocytotic vesicles, were observed in close proximity to the plasmalemma of mesophyll cells (Fig. 3.). By day 14 however, mesophyll cells showed almost complete breakdown of subcellular organelle structure (Fig. 4.), and further evidence for the breakdown of the tonoplast. The final stage of senescence is characterized by the solubilization of the cell wall due to expression and activity of polygalacturonase and/or cellulose. The presence of dictyosomes with associated pinocytotic vesicles formed from the mature face, in close proximity to both the plasmalemma and the cell wall, would appear to support the model proposed by Christopherson for the secretion of cellulase. This pathway of synthesis is typical for secretory glycoproteins.

scholarly journals Cellulose intrafibrillar mineralization of biological silica in a rice plant

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eri Nakamura ◽  
Noriaki Ozaki ◽  
Yuya Oaki ◽  
Hiroaki Imai
Keyword(s):  
Cell Wall ◽  
Silica Nanoparticles ◽  
Epidermal Cell ◽  
Rice Plant ◽  
Cellulose Nanofibers ◽  
Rice Husks ◽  
Vital Activity ◽  
Mineralization Process ◽  
Shape Controlled ◽  
Epidermal Cell Wall

AbstractThe essence of morphological design has been a fascinating scientific problem with regard to understanding biological mineralization. Particularly shaped amorphous silicas (plant opals) play an important role in the vital activity in rice plants. Although various organic matters are associated with silica accumulation, their detailed functions in the shape-controlled mineralization process have not been sufficiently clarified. In the present study, cellulose nanofibers (CNFs) were found to be essential as a scaffold for silica accumulation in rice husks and leaf blades. Prior to silicification, CNFs ~ 10 nm wide are sparsely stacked in a space between the epidermal cell wall and the cuticle layer. Silica nanoparticles 20–50 nm in diameter are then deposited in the framework of the CNFs. The shape-controlled plant opals are formed through the intrafibrillar mineralization of silica nanoparticles on the CNF scaffold.

A freeze-etch study of plant cell walls for ectodesmata

1974 ◽  
Vol 52 (9) ◽  
pp. 2033-2036 ◽  
Author(s):  
N. C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Leaf Tissue ◽  
Physicochemical Characteristics ◽  
Outer Cell ◽  
Plantago Major ◽  
Plant Cell Walls ◽  
Phaseolus Vulgaris L ◽  
Epidermal Cell Wall ◽  
Outer Cell Wall

Leaf tissue of Phaseolus vulgaris L. and Plantago major L. was prepared by the freeze-etch technique and examined in the electron microscope for the presence of ectodesmata. No structures analagous to ectodesmata observed with light microscopy could be found in freeze-etched preparations of chemically unfixed material or in material fixed only in glutaraldehyde. Objects appearing as broad, shallow, granular areas in the epidermal cell wall beneath the cuticle were observed in leaf replicas after fixation in complete sublimate fixative, the acid components of the sublimate fixative, or mercuric chloride alone. Because of their distribution and location, these objects can be considered analagous to ectodesmata observed by light microscopists. Because these areas occur only in chemically fixed walls and are localized within the walls in discrete areas, their presence supports the contention that ectodesmata are sites in the outer cell wall with defined physicochemical characteristics.

Trophoblast transferrin and transferrin receptors in the host–parasite relationship of human pregnancy

1979 ◽  
Vol 204 (1154) ◽  
pp. 83-97 ◽  
Keyword(s):  
Iron Transport ◽  
Light And Electron Microscopy ◽  
Biological Significance ◽  
Transformed Cells ◽  
Specific Factor ◽  
Transferrin Receptors ◽  
Immunological Recognition ◽  
Parasite Relationship ◽  
Cellular Replication ◽  
Host Parasite

Transferrin and specific transferrin receptors are demonstrated on the microvillous surface of syncytiotrophoblast in human immature and term placentae by immunohistological techniques with the use of light and electron microscopy. That the distribution of transferrin is limited to the materno-foetal interface supports the hypothesis that binding of maternal transferrin to trophoblast receptors is involved in the process of iron transport to the foetus. Parallel studies with baboon placentae demonstrate the presence of trophoblast receptors which bind both baboon and human transferrin, thereby putting forward an experimental model which might be used to test the biological significance of placental transferrin receptors in primates. In addition, investigation of a large number of human cell lines shows that many transformed cells, but no normal cells (such as blood lymphocytes) or cells from primary culture (such as neonatal foreskin fibroblasts), possess the ability to bind transferrin to their membranes. These findings suggest that transferrin receptors may play important biological roles in addition to that of iron transport from mother to foetus. One such role could be the limitation of iron in intervillous spaces, thus depriving iron-requiring microorganisms of iron, hence serving as a non-specific factor of resistance for placentae. Another role for foetal transferrin receptors on trophoblasts could be to bind maternal transferrin at the materno-foetal interface, thus frustrating maternal immunosurveillance. This is similar to a mechahism used by schistosomes in the host-parasite relation where host proteins are bound by the parasite to escape immunological recognition. The presence of transferrin receptors on transformed cells suggests that this mechanism might also be employed by tumour cells. Finally, in view of previous studies which show that transferrin is required by stimulated lymphocytes to pass from the G 1 to the S phase of cellular replication, it is proposed that trophoblast transferrin receptors could limit the amount of transferrin in intervillous spaces and thus impede the proliferation and possible cytotoxicity of maternal activated lymphocytes at the materno-foetal interface.

Abnormal skin development in pupoid foetus (pf/pf) mutant mice

Development ◽  
1985 ◽  
Vol 87 (1) ◽  
pp. 47-64
Author(s):  
Chris Fisher ◽  
Edward J. Kollar
Keyword(s):  
Blood Vessels ◽  
Schwann Cells ◽  
Cell Population ◽  
Epidermal Cell ◽  
Basal Lamina ◽  
Mutant Mice ◽  
Nerve Fibres ◽  
Skin Development ◽  
Cell Layers

At 13 days of development the epidermis of mice homozygous for the pupoid foetus (pf/pf) mutation varies in thickness between one and ten cell layers. By 16 days of development cells from the dermis have invaded the epidermis and may be found throughout the epidermis and on its surface. Among these cells are nerve fibres and Schwann cells as well as other unidentified cells. Antibodies directed against fibronectin bind to these abnormal groups of cells in the mutant epidermis and on its surface. A basal lamina, as determined by ultrastructure and by the immuno-fluorescent localization of laminin, was always found at the interface of the mutant epidermis and the invading cell population. By 19 days of development the mutant epidermis is thickened and is permeated by a network of cells including nerve fibres, Schwann cells, blood vessels, and collagen and fibronectin-secreting cells. A basal lamina always separates these groups of invading cells from the epidermal cell population.

Phenolic Deposits and Kranz Syndrome in Leaf Tissues of Spotted (Euphorbia maculata) and Prostrate (Euphorbia supina) Spurge

Weed Science ◽  
1983 ◽  
Vol 31 (1) ◽  
pp. 131-136 ◽  
Author(s):  
C. Dennis Elmore ◽  
Rex N. Paul
Keyword(s):  
Electron Microscopy ◽  
Phenolic Compounds ◽  
Light And Electron Microscopy ◽  
Bundle Sheath ◽  
Fixation Technique ◽  
Mesophyll Cells ◽  
Kranz Anatomy ◽  
Bundle Sheath Cells ◽  
Leaf Tissues ◽  
Sheath Cells

Spotted spurge (Euphorbia maculataL.) and prostrate spurge (E. supinaRaf.), both in subgenusChamesyce,were examined by light and electron microscopy using a caffeine - fixation technique to sequester the phenolic pools intercellularly. Both species have typical dicotyledon-type Kranz anatomy. Sequestered phenolic pools were located in vacuoles in epidermal and mesophyll cells. Only in spotted spurge, however, were additional phenolic pools formed in bundle - sheath cells. This study was undertaken because allelopathy has been demonstrated in prostrate spurge and because phenolic compounds have been implicated in allelopathy. These results would indicate that spotted spurge should also be allelopathic.

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