Histopathology of Fusarium wilt of staghorn sumac (Rhus typhina) caused by Fusarium oxysporum f. sp. callistephi race 3. I. Modes of tissue colonization and pathogen peculiarities

Abstract Light and transmission electron microscope studies of naturally infected or inoculated staghorn sumac plants by Fusarium oxysporum f. sp. callistephi race 3 are reported. Diverse extrinsic material (including latex in some instances) or elements occurred in vessel lumina. Some of this material labelled for pectin, often in association with tyloses, as did other opaque matter in paratracheal cells, related to alterations of their protective layer. Pronounced alterations of pit membranes of bordered pits occurred, with their outer portions disrupted into bodies of opaque matter, strongly labelled for cellulose, and their middle portions as unlabelled shreds. Similarly labelled opaque bodies occasionally occurred on vessel walls and lumina. Direct penetration of host cell secondary walls by the pathogen occurred, but these were degraded to any extent only following intramural invasion. Vessel walls, at all stages of infection, were lined with variously structured matter: in their thinnest forms, by single or paired, equidistant or widely spaced opaque bands, and in their thickest forms as alternating opaque and less opaque layers. Other thin elements, often enclosing opaque material, vesicular structures, or occasionally particles of ribosomal appearance were also delineated by similar but frequently infolded bands. These elements were sometimes observed to be confluent with fungal cells and to label for chitin. Many fungal elements were bound by only a thin or defective lucent wall layer, practically unlabelled for chitin, or by a locally thickened, labelled one; labelling for this substrate was also frequently associated with the fungal cell outer opaque wall layer or with some outer extracellular matter. Fine filamentous structures, connected to fungal cells, to the vessel lining matter, and to these other elements, extended into host walls. The lining itself generally did not label for cellulose or chitin. These observations are discussed in comparison with similar observations made regarding other wilt diseases that we have studied.

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Histopathology of Fusarium wilt of staghorn sumac (Rhus typhina) caused by Fusarium oxysporum f. sp. callistephi race 3. II. Characteristics of opaque matter associated with extensive host cell and cell wall alterations

Phytoprotection ◽

10.7202/013075ar ◽

2006 ◽

Vol 86 (3) ◽

pp. 175-187 ◽

Cited By ~ 5

Author(s):

Guillemond B. Ouellette ◽

Danny Rioux ◽

Marie Simard

Keyword(s):

Fusarium Oxysporum ◽

Wall Layer ◽

Cell Hyperplasia ◽

Transmission Electron ◽

Ray Cells ◽

Host Origin ◽

Histopathology of Fusarium wilt of staghorn sumac (Rhus typhina) caused by Fusarium oxysporum f. sp. callistephi race 3. III. Host cell and tissue reactions

Phytoprotection ◽

10.7202/013967ar ◽

2006 ◽

Vol 87 (1) ◽

pp. 17-27 ◽

Cited By ~ 3

Author(s):

Guillemond B. Ouellette ◽

Mohamed Cherif ◽

Marie Simard

Keyword(s):

Cell Wall ◽

Fusarium Oxysporum ◽

Host Cell ◽

Cross Wall ◽

Tissue Proliferation ◽

Host Cytoplasm ◽

Transmission Electron ◽

Host Cell Wall ◽

Tissue Reactions ◽

Rhus Typhina

Abstract Various cell reactions occurred in staghorn sumac plants inoculated with Fusarium oxysporum f. sp. callistephi. Light and transmission electron microscopy observations and results of cytochemical tests showed: 1) increased laticifers and latex production in the phloem; 2) tylosis formation; 3) host cell wall modifications, including appositions or other cell wall thickenings; and 4) unusual cross wall formation in some cells, and cell hypertrophy and hyperplasia. Tylosis walls labelled for pectin and cellulose and many displayed inner suberin-like layers. These layers were also noted in cells of the medullary sheath and in many cells with dense content and thickened walls in the barrier zones that had formed. These zones also contained fibres with newly-formed gelatinous-like layers. In the vicinity of these cells, host cell walls were frequently altered, associated with opaque matter. Many small particles present in chains also occurred in some of these cells, which contained only remnants of host cytoplasm. Light microscopy observations showed that pronounced tissue proliferation and aberrant cells occurred in the outer xylem in the infected plants. Unusual neoplasmic tissue also formed from cells surrounding the pith and medullary sheath, and it spanned directly across the pre-existing xylem tissue and burst as large mounds on the stems.

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Haustorial development of Peronospora tabacina infecting Nicotiana tabacum

Canadian Journal of Botany ◽

10.1139/b83-388 ◽

1983 ◽

Vol 61 (12) ◽

pp. 3444-3453 ◽

Cited By ~ 3

Author(s):

R. N. Trigiano ◽

C. G. Van Dyke ◽

H. W. Spurr Jr.

Keyword(s):

Cell Wall ◽

Toluidine Blue ◽

Mesophyll Cell ◽

Wall Layer ◽

Peronospora Tabacina ◽

Host Cytoplasm ◽

Transmission Electron ◽

Mold Fungus ◽

Host Cell Wall ◽

Hyphal Wall

The development of haustoria in tobacco by the blue-mold fungus Peronospora tabacina was examined using light, scanning, and transmission electron microscopy. Electron-lucent, callose-like appositions were observed between the host plasmalemma and the host mesophyll cell wall prior to haustorial penetration. An electron-opaque penetration matrix was present between the apposition and the host cell wall. The intercellular hyphal wall consisted of two layers which differed in staining quality. The haustorial wall was also two layered, but was primarily composed of and continuous with the inner wall layer of the intercellular hypha. Haustoria were either finger-like or branched and were encased with callose-like material. Most encasements were thickened at the proximal regions of haustoria but were thinner along the distal portions. Vesicles were present in host cytoplasm and were occasionally attached to the invaginated host plasmalemma. These vesicles might contribute to the deposition of the encasement material. The encasement stained positively for callose using aniline blue; calcofluor and toluidine blue O tests for cellulose were inconclusive, and lignin was not detected using toluidine blue O or phloroglucinol–HCl.

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Contribution à l'étude du Bayoud, fosariose du palmier-dattier. I. Étude du cultivar sensible Deglet-Nour

Canadian Journal of Botany ◽

10.1139/b90-269 ◽

1990 ◽

Vol 68 (10) ◽

pp. 2054-2058 ◽

Cited By ~ 2

Author(s):

Béatrice Mathéron ◽

Abdellatif Benbadis

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Fusarium Oxysporum ◽

Spore Germination ◽

Date Palm ◽

Wilt Disease ◽

Root Epidermis ◽

Bordered Pits ◽

Early Reaction ◽

Scanning Electron

Date palm seedlings were inoculated at the two-leaf stage with Fusarium oxysporum f. sp. albedinis, the causal agent of Bayoud. Following spore germination, hyphae bore a bole through the walls of the root epidermis and penetrated into the cortical parenchyma. The fungus then grows inter- or intra-cellularly towards the central cylinder and enters the xylem vessels. There, it continues to grow towards the leaves. The progression from vessel to vessel is achieved through bordered pits. The cultivar Deglet-Nour, known for its susceptibility to this wilt disease, exhibited no early reaction to the presence of the parasite in its tissues. Key words: date palm, Fusarium oxysporum f. sp. albedinis, scanning electron microscopy.

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Fusarium oxysporum gas1 Encodes a Putative β-1, 3-Glucanosyltransferase Required for Virulence on Tomato Plants

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-18-1140 ◽

2005 ◽

Vol 18 (11) ◽

pp. 1140-1147 ◽

Cited By ~ 46

Author(s):

Zaira Caracuel ◽

Ana Lilia Martínez-Rocha ◽

Antonio Di Pietro ◽

Marta P. Madrid ◽

M. Isabel G. Roncero

Keyword(s):

Cell Wall ◽

Fusarium Oxysporum ◽

Mutational Analysis ◽

Gene Knockout ◽

Colony Growth ◽

Cell Wall Degrading Enzymes ◽

Gene Encoding ◽

Fungal Cell ◽

Ph Response

Glycosylphosphatidylinositol-anchored (β)-1,3-glucanosyltransferases play active roles in fungal cell wall biosynthesis and morphogenesis and have been implicated in virulence on mammals. The role of β-1,3-glucanosyltransferases in pathogenesis to plants has not been explored so far. Here, we report the cloning and mutational analysis of the gas1 gene encoding a putative β-1,3-glucanosyltransferase from the vascular wilt fungus Fusarium oxysporum. In contrast to Candida albicans, expression of gas1 in F. oxysporum was independent of ambient pH and of the pH response transcription factor PacC. Gene knockout mutants lacking a functional gas1 allele grew in a way similar to the wild-type strain in submerged culture but exhibited restricted colony growth on solid substrates. The restricted growth phenotype was relieved by the osmotic stabilizer sorbitol, indicating that it may be related to structural alterations in the cell wall. Consistent with this hypothesis, Δgas1 mutants exhibited enhanced resistance to cell wall-degrading enzymes and increased transcript levels of chsV and rho1, encoding a class V chitin synthase and a small monomeric G protein, respectively. The Δgas1 mutants showed dramatically reduced virulence on tomato, both in a root infection assay and in a fruit tissue-invasion model, thus providing the first evidence for an essential role of fungal β-1,3-glucanosyltransferases during plant infection.

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Cytological studies of the M-haustorium of Endocronartium harknessii: morphology and ontogeny

Canadian Journal of Botany ◽

10.1139/b88-141 ◽

1988 ◽

Vol 66 (5) ◽

pp. 974-988 ◽

Cited By ~ 4

Author(s):

A. A. Hopkin ◽

J. Reid

Keyword(s):

Pinus Banksiana ◽

Phosphotungstic Acid ◽

Chromic Acid ◽

Periodic Acid ◽

Neck Region ◽

Wall Layer ◽

Calcofluor White ◽

Transmission Electron ◽

Endocronartium Harknessii ◽

The Matrix

M-haustoria of the endocyclic rust Endocronartium harknessii (J. P. Moore) Y. Hirat. were examined with light and transmission electron microscopy in infected seedlings of Pinus banksiana Lamb. The haustoria developed from unspecialized cells of the intercellular hyphae, each of which appeared capable of producing several haustoria. The haustoria were distinct from the intercellular hyphae in possessing a narrow septate neck region which terminated in a globose haustorial body. Periodic acid – thiocarbohydrazide – silver proteinate and periodic acid – chromic acid – phosphotungstic acid staining provided evidence of an additional wall layer in the haustorial neck not evident in the intercellular hyphae and suggested that the extra-haustorial matrix contained polysaccharides of mixed linkage as well as lipids. However, cellulase extraction and the use of gold-bound wheat-germ lectin showed that neither cellulose nor chitin, respectively, was a component of the matrix. Both the haustoria and the matrix were separated from the host cytoplasm by the extrahaustorial membrane. This membrane stained positively with periodic acid – chromic acid – phosphotungstic acid, while the noninvaginated portion of the host plasmalemma with which it was continuous usually did not. The matrix fluoresced strongly when stained with aniline blue in an apparently compatible reaction. Other stains such as analinonapthalenesulphonic acid and Calcofluor white showed evidence of protein and polysaccharide in the fungal walls. Light and transmission electron microscope observations showed that penetration pegs formed as narrow tubular evaginations of the haustorial mother cell which caused inward displacement of the host cell wall. They retained their peg-like appearance as they entered the cell lumen, but eventually their distal ends enlarged to form typical globose haustorial bodies.

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Fine structural observations on substances attributable to Ceratocystis ulmi in American elm and aspects of host cell disturbances

Canadian Journal of Botany ◽

10.1139/b78-309 ◽

1978 ◽

Vol 56 (20) ◽

pp. 2550-2566 ◽

Cited By ~ 14

Author(s):

G. B. Ouellette

Keyword(s):

Host Cell ◽

Cell Walls ◽

Parenchyma Cell ◽

Dutch Elm Disease ◽

Similar Material ◽

Fungal Cell ◽

Fibrillar Material ◽

American Elm ◽

Vessel Walls ◽

Parenchyma Cell Walls

Plugging of certain vessels may occur in elm shortly after inoculation with the Dutch elm disease pathogen, Ceratocystis ulmi (Buism.) C. Moreau. Plugging components include fibrillar material of varying density and fungal cells traceable mostly to inoculated spores. Some material is similar to fungal cell contents, and indications of extrusion of the latter through ruptured or unruptured walls were obtained. Other material is also attributable to disintegrating fungal walls. Radioautographs obtained from samples treated with [6-3H]thymidine indicate significant labeling of fungal cell contents and of similar material, free.Similar fibrillar material, some labeled, is present within pit membranes, in adjacent parenchyma cell walls, and in periplasmic areas associated with retraction of the plasmalemma and with other cytoplasmic disturbances. Host vessel walls are also altered in the presence of some fibrillar material but apparently release only limited amounts of disintegration products into vessels.The possible implications of these observations are discussed in relation to current hypotheses on wilt diseases.

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Effect of household bleach on the structure of the sporocyst wall of Toxoplasma gondii

Parasite ◽

10.1051/parasite/2021066 ◽

2021 ◽

Vol 28 ◽

pp. 68

Author(s):

Aurélien Dumètre ◽

Jitender P. Dubey ◽

David J.P. Ferguson

Keyword(s):

Toxoplasma Gondii ◽

Outer Layer ◽

Wall Layer ◽

Cross Link ◽

Oocyst Wall ◽

Maclura Pomifera ◽

Transmission Electron ◽

Household Bleach ◽

Sporocyst Wall ◽

Molecular Nature

Toxoplasma gondii oocysts are responsible for food- and water-borne infections in humans worldwide. They are resistant to common chemical disinfectants, including chlorinated products, presumably due to the structure and molecular nature of the oocyst wall but also the sporocyst wall. In this study, we used fluorescence microscopy and transmission electron microscopy to characterise the structure of both the oocyst and sporocyst walls, exposed to household bleach. Bleach removed the outer layer of the oocyst wall and the outer layer of the wall of sporocysts exposed due to rupture of the oocyst wall. The loss of the outer sporocyst wall layer was associated with a decrease in its autofluorescence, which can be linked to the degradation of dityrosine cross-link proteins, and loss of Maclura pomifera lectin-reactive glycoproteins. This study suggests that the inner layers of the oocyst and sporocyst walls are the main structures responsible for the resistance of the parasite to household bleach.

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Alterations in Mycelial Morphology and Flow Cytometry Assessment of Membrane Integrity of Ganoderma boninense Stressed by Phenolic Compounds

Biology ◽

10.3390/biology10090930 ◽

2021 ◽

Vol 10 (9) ◽

pp. 930

Author(s):

Daarshini Ganapathy ◽

Yasmeen Siddiqui ◽

Khairulmazmi Ahmad ◽

Fariz Adzmi ◽

Kong Lih Ling

Keyword(s):

Electron Microscopy ◽

Phenolic Compounds ◽

Membrane Integrity ◽

Cell Integrity ◽

Ganoderma Boninense ◽

Fungal Cell ◽

Antifungal Effect ◽

Basal Stem Rot ◽

Transmission Electron ◽

Global Increase

Global increase in demand for palm oil has caused an intensification in oil palm plantation; however, production is greatly hindered by Basal Stem Rot (BSR) disease caused by Ganoderma boninense. There are many approaches to controlling BSR, although, there is no accurate, sustainable and effective method to suppress G. boninense completely. Hence, four phenolic compounds [Gallic acid (GA), Thymol (THY), Propolis (PRO) and Carvacrol (CARV)] were selected to evaluate their antifungal effect, ability to alter the mycelium morphology, and fungal cell integrity against G. boninense. Significant differences (p < 0.05) were observed and 94% of inhibition was exerted by GA on G. boninense growth. Scanning Electron Microscopy and High-Resolution Transmission Electron Microscopy observations revealed that GA and THY treatment caused severe damage to the mycelium and recorded the highest amount of sugar and electrolyte leakage. The study of cell integrity and morphological disruption has elucidated the reduction of G. boninense cell viability. Generally, our findings confirm the fungistatic effects of GA and THY. The evolution of phenolic compounds during the phytopathology studies indicated their coherence in eradicating the G. boninense. It is proposed that GA and THY had the potential to be developed further as a natural antifungal treatment to suppress G. boninense.

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Gum Arabic Nanoparticles as Green Corrosion Inhibitor for Reinforced Concrete Exposed to Carbon Dioxide Environment

Materials ◽

10.3390/ma14247867 ◽

2021 ◽

Vol 14 (24) ◽

pp. 7867

Author(s):

Mohammad Ali Asaad ◽

Ghasan Fahim Huseien ◽

Mohammad Hajmohammadian Baghban ◽

Pandian Bothi Raja ◽

Roman Fediuk ◽

...

Keyword(s):

Electron Microscopy ◽

Carbon Dioxide ◽

Reinforced Concrete ◽

Electrochemical Impedance ◽

Protective Layer ◽

Gum Arabic ◽

Steel Reinforcement ◽

X Ray ◽

Transmission Electron ◽

Carbonation Resistance

The inhibiting effect of Gum Arabic-nanoparticles (GA-NPs) to control the corrosion of reinforced concrete that exposed to carbon dioxide environment for 180 days has been investigated. The steel reinforcement of concrete in presence and absence of GA-NPs were examined using various standard techniques. The physical/surface changes of steel reinforcement was screened using weight loss measurement, electrochemical impedance spectroscopy (EIS), atomic force microscopy and scanning electron microscopy (SEM). In addition, the carbonation resistance of concrete as well screened using visual inspection (carbonation depth), concrete alkalinity (pH), thermogravimetric analysis (TGA), SEM, energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The GA-NPs inhibitor size was also confirmed by transmission electron microscopy (TEM). The results obtained revealed that incorporation of 3% GA-NPs inhibitor into concrete inhibited the corrosion process via adsorption of inhibitor molecules over the steel reinforcement surface resulting of a protective layer formation. Thus, the inhibition efficiency was found to increase up-to 94.5% with decreasing corrosion rate up-to 0.57 × 10−3 mm/year. Besides, the results also make evident the presence of GA-NPs inhibitor, ascribed to the consumption of calcium hydroxide, and reduced the Ca/Si to 3.72% and 0.69% respectively. Hence, C-S-H gel was developed and pH was increased by 9.27% and 12.5, respectively. It can be concluded that green GA-NPs have significant corrosion inhibition potential and improve the carbonation resistance of the concrete matrix to acquire durable reinforced concrete structures.

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