Cytological studies of the hypersensitive death of cowpea epidermal cells induced by basidiospore-derived infection by the cowpea rust fungus

1991 ◽  
Vol 69 (6) ◽  
pp. 1199-1206 ◽  
Author(s):  
C. Y. Chen ◽  
Michele C. Heath
Keyword(s):  
Hypersensitive Response ◽  
Cell Walls ◽  
Cytoplasmic Streaming ◽  
Rust Fungus ◽  
Fungal Growth ◽  
Inhibitory Effect ◽  
Epidermal Cells ◽  
Plant Cell Walls ◽  
Powdery Mildew Fungus ◽  
Uromyces Vignae

The cytological responses to the monokaryotic primary hyphae of the cowpea rust fungus (Uromyces vignae Barcl.) were observed in vein epidermal cells of a resistant and a susceptible cowpea cultivar. Unlike the previously examined response to haustoria of a nonpathogenic powdery mildew fungus, plant cell walls did not become autofluorescent in response to fungal penetration, and the primary hypha only rarely became encased. Following fungal penetration, the response of invaded cells of the resistant, intact plant could be divided into the following stages: (I) cytoplasmic streaming normal; (II) cytoplasmic streaming slow or stopped, Brownian motion of particles visible in the vacuole, granulated cytoplasm aggregated along the cell walls, some host nuclei disappeared; and (III) protoplast collapsed. Epidermal tissue of the resistant cultivar did not exhibit stages II–III when detached and mounted in water 12 h after inoculation and examined 9 h later. The frequency of stage III increased when the tissue was mounted in CaCl2, Ca(NO3)2, and KNO3, but only in a kinetin solution did it approximate that in attached tissue. Although kinetin inhibited fungal growth in both the resistant and the susceptible cultivar, the hypersensitive response occurred only in the former, suggesting that kinetin affects the hypersensitive response directly rather than through its inhibitory effect on the fungus. Key words: cowpea, Vigna unguiculata, cowpea rust fungus, Uromyces vignae (Barcl.), hypersensitivity.

A comparison of the death induced by fungal invasion or toxic chemicals in cowpea epidermal cells. II. Responses induced by Erysiphe cichoracearum

1988 ◽  
Vol 66 (4) ◽  
pp. 624-634 ◽  
Author(s):  
Susan L. F. Meyer ◽  
Michèle C. Heath
Keyword(s):  
Electron Microscopy ◽  
Cytoplasmic Streaming ◽  
Epidermal Cells ◽  
Toxic Chemicals ◽  
Ultrastructural Changes ◽  
Powdery Mildew Fungus ◽  
Fresh Tissue ◽  
Golgi Bodies ◽  
Erysiphe Cichoracearum ◽  
Cytoplasmic Aggregate

Cowpea leaves were inoculated with the plantain powdery mildew fungus, Erysiphe cichoracearum, and fresh epidermal cells overlying veins were examined by light microscopy before being cleared or prepared for electron microscopy. Fungal appressoria usually formed a haustorium in the underlying nonhost cell, but only after what appeared to be an unsuccessful penetration attempt that induced a transient cytoplasmic aggregate, a ring of autofluorescence in the plant wall (best seen in cleared tissue), and in two examples observed ultrastructurally, a small penetration peg embedded in a callose-like papilla. The haustorium developed from a different penetration peg and elicited the death of the invaded cell. As reported for the death of cowpea epidermal cells elicited by CuCl2, cytoplasmic changes that occurred rapidly in fresh tissue after cytoplasmic streaming had stopped correlated closely with changes in ultrastructure. Compared with the CuCl2 study, microtubules and Golgi bodies disappeared faster and membranes appeared more disorganized. These data suggest that in cowpea epidermal cells, ultrastructural changes accurately predict the onset of cell death and may also reflect differences in its modes of induction.

Genetics and cytology of age-related resistance in North American cultivars of cowpea (Vigna unguiculata) to the cowpea rust fungus (Uromyces vignae)

1994 ◽  
Vol 72 (5) ◽  
pp. 575-581 ◽  
Author(s):  
Michèle C. Heath
Keyword(s):  
Resistance Gene ◽  
Rust Fungus ◽  
Leaf Age ◽  
Fungal Growth ◽  
Individual Plant ◽  
Infection Site ◽  
Age Related ◽  
Race 1 ◽  
Uromyces Vignae ◽  
Site Types

Increasing leaf age was accompanied by increases in resistance in three incompatible cowpea cultivars inoculated with race 1 of Uromyces vignae and in three of four cultivars that had previously been considered susceptible to race N2. Selected crosses between cultivars suggested that resistance to race 1 was controlled by the same genes in young and old leaves, and they indicated that age-related resistance to race N2 was primarily controlled by a single, and different, gene in each cultivar. All examples of resistance were expressed cytologically as a range of infection site types in a single leaf, the frequency distribution of which was affected by the type of resistance gene, gene heterozygosity, and leaf age. These frequency distributions shifted with increasing leaf age towards infection sites with less fungal growth and more rapid plant cell necrosis, often abolishing the cytological differences between cultivars and genotypes seen in younger plants. The data suggest that each rust resistance gene in cowpea can generate a range of infection site types, and that fungal growth and plant responses at each infection site are governed by a combination of the number and type of resistance genes in the plant, the race of the fungus, and age-affected features of individual plant cells. Key words: cowpea, rust fungi, age-related resistance.

Changes in leaves of susceptible and resistant Solanum dulcamara infested by the gall mite Eriophyes cladophthirus (Acarina, Eriophyoidea)

1981 ◽  
Vol 59 (5) ◽  
pp. 875-882 ◽  
Author(s):  
E. Westphal ◽  
R. Bronner ◽  
M. Le Ret
Keyword(s):  
Hypersensitive Response ◽  
Cell Walls ◽  
Polyphenolic Compounds ◽  
Epidermal Cells ◽  
Solanum Dulcamara ◽  
Injured Cell ◽  
Feeding Sites ◽  
Gall Mite ◽  
Necrotic Region

Eriophyes cladophthirus perforates the wall of epidermis cells during feeding on young susceptible leaves and provokes the formation of cone-shaped feeding punctures. Callose is detected near the puncture after 20 min and the injured cells are transformed into nutritive cells. Nutritive cells are induced near the feeding sites on susceptible plants, whereas only necrotic cells appear near feeding sites on resistant plants.Mites feeding on resistant plants rapidly initiate a hypersensitive response detectable after 10 min on injured epidermal cells which then leads to severe necrosis of surrounding tissues after 1 h. No typical feeding punctures or callose deposits appear on injured cell walls. Polyphenolic compounds are detected in the necrotic region after 4 h.

Light and electron microscopy of the interaction between the sunflower rust fungus (Puccinia helianthi) and leaves of the nonhost plant, French bean (Phaseolus vulgaris)

1986 ◽  
Vol 64 (11) ◽  
pp. 2476-2486 ◽  
Author(s):  
Lesley A. Wood ◽  
Michèle C. Heath
Keyword(s):  
Heat Treatment ◽  
Cell Walls ◽  
Rust Fungus ◽  
Light And Electron Microscopy ◽  
Fungal Growth ◽  
Mesophyll Cell ◽  
French Bean ◽  
Puccinia Helianthi ◽  
Mother Cells ◽  
Bean Leaves

Growth of the sunflower rust fungus (Puccinia helianthi Schw.) was compared by light microscopy in sunflower leaves, in untreated French bean leaves, in bean leaves given a preinoculation heat treatment, and on collodion membranes. Results suggested that fungal growth was slightly reduced and the formation of haustorial mother cells was inhibited in untreated bean leaves. Haustorial mother cells, when present, did not form haustoria and adjacent mesophyll cell walls usually were highly refractive. Preinoculation heat treatment reduced the incidence of refractive cell walls and increased that of haustorial mother cells and haustoria. Ultrastructurally, infection hyphae in unheated bean leaves appeared unusually vacuolate and often contained wall appositions where they touched the plant cells. Silicalike deposits were present in and on mesophyll cell walls at most infection sites. In heated plants, necrotic haustoria with small bodies were seen at the few sites that lacked silicalike deposits. At other sites, the fungus appeared to have stopped growing during the formation of the penetration peg or the haustorial neck, and such necks were encrusted with silicalike material. At most sites, penetration pegs were occluded resulting in the unusual situation in which the haustorial mother cell remained seemingly alive in spite of the necrosis of the haustorium.

Exploration of cell wall architecture with the rapid-freeze deep-etch technique

1993 ◽  
Vol 51 ◽  
pp. 128-129
Author(s):  
Béatrice Satiat-Jeunemaitre ◽  
Chris Hawes
Keyword(s):  
Plant Cell ◽  
Cell Walls ◽  
Cell Biology ◽  
Molecular Model ◽  
Three Dimensional ◽  
Secretory Activity ◽  
Wall Structure ◽  
Specimen Preparation ◽  
Molecular Architecture ◽  
Plant Cell Walls

The comprehension of the molecular architecture of plant cell walls is one of the best examples in cell biology which illustrates how developments in microscopy have extended the frontiers of a topic. Indeed from the first electron microscope observation of cell walls it has become apparent that our understanding of wall structure has advanced hand in hand with improvements in the technology of specimen preparation for electron microscopy. Cell walls are sub-cellular compartments outside the peripheral plasma membrane, the construction of which depends on a complex cellular biosynthetic and secretory activity (1). They are composed of interwoven polymers, synthesised independently, which together perform a number of varied functions. Biochemical studies have provided us with much data on the varied molecular composition of plant cell walls. However, the detailed intermolecular relationships and the three dimensional arrangement of the polymers in situ remains a mystery. The difficulty in establishing a general molecular model for plant cell walls is also complicated by the vast diversity in wall composition among plant species.

Wheat cell walls and constituent polysaccharides induce similar microbiota profiles upon in vitro fermentation despite different short chain fatty acid end-product levels.

2021 ◽  
Author(s):  
Shiyi Lu ◽  
Deirdre Mikkelsen ◽  
Hong Yao ◽  
Barbara Williams ◽  
Bernadine Flanagan ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Gut Microbiota ◽  
Plant Cell ◽  
Cell Walls ◽  
Short Chain Fatty Acid ◽  
Chain Fatty Acid ◽  
Plant Cell Walls ◽  
Human Gut ◽  
In Vitro Fermentation

Plant cell walls as well as their component polysaccharides in foods can be utilized to alter and maintain a beneficial human gut microbiota, but it is not known whether the...

scholarly journals Plant Cell Wall Hydration and Plant Physiology: An Exploration of the Consequences of Direct Effects of Water Deficit on the Plant Cell Wall

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1263
Author(s):  
David Stuart Thompson ◽  
Azharul Islam
Keyword(s):  
Cell Wall ◽  
Water Content ◽  
Bacterial Cellulose ◽  
Plant Cell ◽  
Cell Walls ◽  
Plant Cell Wall ◽  
Plant Cell Walls ◽  
Cell Wall Polysaccharides ◽  
Degree Of Hydration ◽  
Cellulose Composites

The extensibility of synthetic polymers is routinely modulated by the addition of lower molecular weight spacing molecules known as plasticizers, and there is some evidence that water may have similar effects on plant cell walls. Furthermore, it appears that changes in wall hydration could affect wall behavior to a degree that seems likely to have physiological consequences at water potentials that many plants would experience under field conditions. Osmotica large enough to be excluded from plant cell walls and bacterial cellulose composites with other cell wall polysaccharides were used to alter their water content and to demonstrate that the relationship between water potential and degree of hydration of these materials is affected by their composition. Additionally, it was found that expansins facilitate rehydration of bacterial cellulose and cellulose composites and cause swelling of plant cell wall fragments in suspension and that these responses are also affected by polysaccharide composition. Given these observations, it seems probable that plant environmental responses include measures to regulate cell wall water content or mitigate the consequences of changes in wall hydration and that it may be possible to exploit such mechanisms to improve crop resilience.

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