Callose deposition during the interaction between cowpea (Vigna unguiculata) and the monokaryotic stage of the cowpea rust fungus (Uromyces vignae)

1997 ◽  
Vol 136 (3) ◽  
pp. 511-524 ◽  
Author(s):  
DUBRAVKA SKALAMERA ◽  
STEFAN JIBODH ◽  
MICHELE C. HEATH
Keyword(s):  
Vigna Unguiculata ◽  
Rust Fungus ◽  
Callose Deposition ◽  
Uromyces Vignae

Changes in the plant endomembrane system associated with callose synthesis during the interaction between cowpea (Vigna unguiculata) and the cowpea rust fungus (Uromyces vignae)

1995 ◽  
Vol 73 (11) ◽  
pp. 1731-1738 ◽  
Author(s):  
Dubravka Škalamera ◽  
Michèle C. Heath
Keyword(s):  
Endoplasmic Reticulum ◽  
Vigna Unguiculata ◽  
De Novo ◽  
Rust Fungus ◽  
Leaf Tissue ◽  
Resistant Cultivar ◽  
Callose Deposition ◽  
Golgi Membranes ◽  
Rough Er ◽  
Uromyces Vignae

Electron microscopy and stereological analysis of cowpea (Vigna unguiculata) leaf tissue infected with the cowpea rust fungus (Uromyces vignae) revealed an increase in surface of plant endomembranes that was associated with callose synthesis or the presence of fungal haustoria. In the resistant cultivar in which the haustorium commonly becomes encased, an increase in surface of smooth membranes was observed in cytoplasmic regions adjacent to developing encasements compared with the regions away from the fungus or with any region in infected or uninfected callose nonsynthesizing cells. Cytoplasmic regions adjacent to the haustorium in callose nonsynthesizing cells had an increase in rough endoplasmic reticulum (ER). This increase was greater in a susceptible cultivar than in the resistant cultivar that was treated with tunicamycin to inhibit callose synthesis. In the latter situation, the lack of callose encasement allowed the haustorial neckband to form, but other ultrastructural signs of incompatibility remained, such as the presence of electron-opaque material associated with the extrahaustorial membrane. No differences between cultivars or treatments were observed in Golgi membranes. Our observations suggest that both callose synthesis and fungal presence are associated with de novo synthesis of membranes; callose deposition may require an increase in smooth membranes of uncertain origin, whereas the establishment of a haustorium may be dependent on increased synthesis of rough ER. Key words: callose, endoplasmic reticulum, resistance, stereology, tunicamycin.

Non-host resistance responses of Arabidopsis thaliana to the coffee leaf rust fungus (Hemileia vastatrix)

Botany ◽  
2010 ◽  
Vol 88 (7) ◽  
pp. 621-629 ◽  
Author(s):  
Helena Gil Azinheira ◽  
Maria do Céu Silva ◽  
Pedro Talhinhas ◽  
Clara Medeira ◽  
Isabel Maia ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Leaf Rust ◽  
Rust Fungus ◽  
Hemileia Vastatrix ◽  
Callose Deposition ◽  
Mesophyll Cells ◽  
Model Plant ◽  
Heterologous System ◽  
Coffee Leaf Rust ◽  
Model Plant Arabidopsis Thaliana

Leaf rust, caused by Hemileia vastatrix Berk & Broome, is the most destructive fungal disease of coffee. In the absence of a suitable gene validation system in coffee, the objective of this study was to investigate whether the model plant Arabidopsis thaliana (L.) Heynh. may be used as a heterologous system for the molecular dissection of coffee responses to leaf rust. Histological examination of A. thaliana (Col-0) leaves inoculated with H. vastatrix (race II) showed that by 24 h after inoculation (hai), H. vastatrix uredospores differentiated appressoria and penetrated the stomata, but failed to form haustoria. Arabidopsis thaliana cellular resistance responses included hypersensitive-like response (HR) of stomata guard cells together with accumulation of phenolic compounds and callose deposition in walls of epidermal and mesophyll cells. Results indicate that H. vastatrix infection triggered the induction of a set of defence-related genes peaking at 18 and 42 hai. The non-host HR triggered by H. vastatrix in the model plant A. thaliana makes it usable to infer the function of coffee genes involved in pre-haustorial rust resistance.

Haustorial mother cell development by Uromyces vignae on collodion membranes

1988 ◽  
Vol 66 (4) ◽  
pp. 736-741 ◽  
Author(s):  
Michèle C. Heath ◽  
C. J. Perumalla
Keyword(s):  
Cell Wall ◽  
Mother Cell ◽  
Rust Fungus ◽  
Potential Binding ◽  
Disulphonic Acid ◽  
Uromyces Vignae ◽  
Mother Cells ◽  
Chloroform Methanol ◽  
Infection Hypha ◽  
Mother Cell Wall

The development of infection structures by the rust fungus Uromyces vignae was observed on oil-containing collodion membranes. About 40% of infection hyphae formed a haustorial mother cell, but this structure commonly senesced and died more rapidly than the infection hypha to which it was attached. These data suggest that the continued development of the haustorial mother cell requires some component normally provided by the host plant. Before they died, many haustorial mother cells apparently formed the thickened region of the wall which normally is traversed by the penetration peg during haustorium formation. Such a peg was observed in the centre of up to 40% of these thickened regions. However, no pegs protruded beyond the haustorial mother cell far enough to be called a haustorial neck. The thickened region of the haustorial mother cell wall could be differentiated from the rest of the wall by its lack of fluorescence under ultraviolet irradiation when mounted in Calcofluor or SITS (4-acetomido-4′-iso-thiocyanatostilbene-2,2′-disulphonic acid). Treatment with alkali, acid, chloroform–methanol, protease, and laminarinase did not affect this differential fluorescence, and the haustorial mother cell wall stained uniformly for proteins, carbohydrates, and chitin. Since Calcofluor normally binds to chitin, these data suggest that the thickened region of the haustorial mother cell wall may physically exclude the dye or may contain potential binding sites that are masked by other wall components.

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.

scholarly journals An effector protein of the wheat stripe rust fungus targets chloroplasts and suppresses chloroplast function

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Qiang Xu ◽  
Chunlei Tang ◽  
Xiaodong Wang ◽  
Shutian Sun ◽  
Jinren Zhao ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Stripe Rust ◽  
Puccinia Striiformis ◽  
Rust Fungus ◽  
Fungal Growth ◽  
Microbial Pathogens ◽  
Virus Induced Gene Silencing ◽  
Callose Deposition ◽  
Wheat Stripe Rust ◽  
Stripe Rust Fungus

AbstractChloroplasts are important for photosynthesis and for plant immunity against microbial pathogens. Here we identify a haustorium-specific protein (Pst_12806) from the wheat stripe rust fungus, Puccinia striiformis f. sp. tritici (Pst), that is translocated into chloroplasts and affects chloroplast function. Transient expression of Pst_12806 inhibits BAX-induced cell death in tobacco plants and reduces Pseudomonas-induced hypersensitive response in wheat. It suppresses plant basal immunity by reducing callose deposition and the expression of defense-related genes. Pst_12806 is upregulated during infection, and its knockdown (by host-induced gene silencing) reduces Pst growth and development, likely due to increased ROS accumulation. Pst_12806 interacts with the C-terminal Rieske domain of the wheat TaISP protein (a putative component of the cytochrome b6-f complex). Expression of Pst_12806 in plants reduces electron transport rate, photosynthesis, and production of chloroplast-derived ROS. Silencing TaISP by virus-induced gene silencing in a susceptible wheat cultivar reduces fungal growth and uredinium development, suggesting an increase in resistance against Pst infection.

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.

Cellular mechanisms of callose deposition in response to fungal infection or chemical damage

1996 ◽  
Vol 74 (8) ◽  
pp. 1236-1242 ◽  
Author(s):  
Dubravka Škalamera ◽  
Michèle C. Heath
Keyword(s):  
Protein Synthesis ◽  
Boric Acid ◽  
Rust Fungus ◽  
Brefeldin A ◽  
Protein Glycosylation ◽  
Cellular Mechanisms ◽  
Callose Deposition ◽  
Cellular Processes ◽  
Microtubule Polymerization ◽  
Chemical Inhibitors

Cellular mechanisms of callose deposition induced in cowpea (Vigna unguiculata) leaves by the living cowpea rust fungus (Uromyces vignae), boric acid, or the fungus killed by polyoxin D, were investigated by the use of chemical inhibitors. Effects of the inhibitors were observed in both a resistant and a susceptible cowpea cultivar. The effect of inhibitors differed depending on the type of callose-inducing stimulus and cultivar used. Inhibitors of transcription (actinomycin D) and protein synthesis (blasticidin S, cycloheximide) lowered the incidence of fungus-induced callose deposits in both cultivars. Inhibitors of protein synthesis also reduced deposits induced by boric acid or fungal death. Callose deposition induced by the living fungus in the resistant cultivar was reduced by inhibitors of protein glycosylation (tunicamycin, deoxynojirimycin) and microfilament function (cytochalasins B and E), but these inhibitors had no effect on callose deposition in the susceptible cultivar or on chemical or fungal death-induced deposition in either cultivar. No reduction in callose deposits was observed in plants treated with inhibitors of Golgi-associated vesicle transfer (brefeldin A, monensin) or microtubule polymerization (colchicine, oryzalin). The results suggest that the cellular processes involved in callose deposition differ with differing triggering stimuli and that callose deposition triggered by the living fungus in a resistant host cultivar is not a typical wound or damage response. Keywords: callose, infection, inhibitors, resistance, rust fungi.

scholarly journals Differentiation of aecidiospore- and uredospore-derived infection structures on cowpea leaves and on artificial surfaces by Uromyces vignae

1993 ◽  
Vol 71 (9) ◽  
pp. 1236-1242 ◽  
Author(s):  
M. Stark-Urnau ◽  
K. Mendgen
Keyword(s):  
Key Words ◽  
Mother Cell ◽  
Host Plants ◽  
Rust Fungus ◽  
Host Cells ◽  
In Planta ◽  
Infection Structures ◽  
Artificial Surfaces ◽  
Uromyces Vignae ◽  
Mother Cells

Aecidiospores and uredospores are the two dikaryotic spore forms of the cowpea rust fungus Uromyces vignae. After germination they can be induced to develop a series of infection structures including appressoria, infection hyphae, and haustorial mother cells. Haustoria are then formed within host cells. The differentiation of infection structures was compared on polystyrene membranes with defined topographies, on scratched polyethylene membranes, and in planta. On polystyrene membranes with defined topographies both sporelings showed highest rates of differentiation on ridges 0.3 μm high but aecidiosporelings responded less efficiently to this stimulus than uredosporelings. On scratched polyethylene membranes, almost 90% of both sporelings differentiated appressoria, but only 10% formed haustorial mother cells; haustoria were not observed. On the host plant, by contrast, only 50% of the sporelings differentiated appressoria, but most of these formed haustorial mother cells and haustoria. In planta haustorial mother cell development occurred approximately 6 h earlier than on inductive membranes. Infection structures formed on artificial membranes and on host plants were similar in morphology and nuclear condition. Key words: cowpea rust fungus, nucleus, appressorium.

scholarly journals Early events in living epidermal cells of cowpea and broad bean during infection with basidiospores of the cowpea rust fungus

1991 ◽  
Vol 69 (10) ◽  
pp. 2279-2285 ◽  
Author(s):  
Haixin Xu ◽  
Kurt Mendgen
Keyword(s):  
Vicia Faba ◽  
Broad Bean ◽  
Rust Fungus ◽  
Infection Process ◽  
Host Cells ◽  
Appressorium Formation ◽  
Vigna Sinensis ◽  
Infected Cells ◽  
Uromyces Vignae ◽  
Defence Reactions

The infection process of basidiospores of the cowpea rust fungus (Uromyces vignae) was studied on living host (Vigna sinensis) and nonhost (Vicia faba) leaves using light microscopy with differential interference contrast optics. During the first 8 h, fungal development was similar on host and on nonhost leaves. Penetration and production of intraepidermal vesicles occurred in nonhost cells 4 h earlier than in host cells. Penetration frequency was also higher in nonhost leaves. These results suggest that the cuticle of the cowpea plant delays basidiospore infection. Both host and nonhost cells produced cytoplasmic aggregates during appressorium formation and again, a few hours later, during penetration of the epidermal cell wall. Cytoplasmic aggregates were also observed in cells adjacent to a collapsing cell. Papillae were observed at most infection sites in both host and nonhost cells. The nuclei of infected cells migrated towards the penetration site in both plant–pathogen combinations. Nuclear size increased considerably only in the nonhost epidermis and decreased again markedly after cell collapse. In the nonhost cells, three types of defence reactions occurred during or after formation of the intraepidermal vesicle. First, following the halt of cytoplasmic streaming, the cytoplasm of the invaded cell either contracted or disintegrated into granules. Alternatively, the cytoplasm continued streaming but darkly pigmented material encased the fungal infection structure. Key words: basidiospore, broad bean (Vicia faba), cowpea (Vigna sinensis), cowpea rust fungus (Uromyces vignae), hypersensitivity, nonhost resistance.

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