Ultrastructure of teliospore formation in the cedar-apple rust fungus Gymnosporangium juniperi-virginianae

1977 ◽  
Vol 55 (17) ◽  
pp. 2319-2329 ◽  
Author(s):  
Charles W. Mims
Keyword(s):  
Mother Cell ◽  
Rust Fungus ◽  
Terminal Cell ◽  
Sporogenous Cell ◽  
Synaptonemal Complexes ◽  
Binucleate Cells ◽  
Cell Functions ◽  
Basal Septum ◽  
Initial Forms

A telium of G. jttniperi-virginianae consists of a palisade-like layer of hyphae located beneath the host epidermis. The terminal cell of each hypha within the telium disintegrates before the onset of teliospore formation. The cell immediately beneath the terminal cell functions as a sporogenous cell giving rise to teliospore initials. Each sporogenous cell contains two nuclei which divide mitotically as each initial forms. Two daughter nuclei move into the teliospore initial and two remain in the sporogenous cell. The initial elongates and is delimited from the sporogenous cell by a basal septum. The nuclei within the initial then divide and a centripetally developing septum separates the initial into two binucleate cells. The lower cell dies and becomes the pedicel of the spore while the upper cell or teliospore mother cell continues to develop. The nuclei of the mother cell divide and a centripetally developing central septum divides the cell into two binucleate cells. At this stage, the young teliospore is delimited. Its wall thickens and the spore enlarges, becoming more ellipsoid. Eventually, the nuclei within each cell of the teliospore fuse. After karyogamy, synaptonemal complexes appear in the nuclei of spores still within the telium.

The temporal relationship between the development of intracellular hyphae and haustoria by Physopella zeae in Zea mays

1988 ◽  
Vol 66 (4) ◽  
pp. 742-744 ◽  
Author(s):  
Michèle C. Heath ◽  
M. R. Bonde
Keyword(s):  
Plant Cell ◽  
Mother Cell ◽  
Plant Cell Wall ◽  
Rust Fungus ◽  
Morphological Differentiation ◽  
Adjacent Cell ◽  
Previous Suggestion ◽  
Epidermal Tissue ◽  
Developmental Relationship ◽  
Mother Cells

To investigate the developmental relationship between haustoria and intracellular hyphae, fixed and cleared whole mounts of com leaves infected with the tropical corn rust fungus Physopella zeae (Mains) Cumm. & Ramachar were examined by interference contrast light microscopy. Haustoria were clearly distinguished from intracellular hyphae by their morphological differentiation into a filamentous body and a narrow neck. The latter was encircled by a thin neckband, which appeared to develop in young haustoria at the time when the haustorial body started to expand. Observations made at the colony margins suggested that the fungus grew into uninvaded epidermal tissue in the following sequence: (i) formation of a haustorium from a haustorial mother cell in an adjacent cell, (ii) formation of an intracellular hypha next to the haustorium by the same intracellular hypha that had formed the haustorial mother cell, (iii) growth of the intracellular hypha within the newly invaded plant cell, (iv) formation by the intracellular hyphae of haustorial mother cells against the plant cell wall adjacent to an uninvaded cell, and (v) formation of haustoria in the uninvaded cell. These results support the previous suggestion that the haustorium may induce a state of susceptibility in the plant cell, "paving the way" for invasion by the intracellular hyphae.

Cytochemical studies on Puccinia graminis f. sp. tritici in a compatible wheat host. II. Haustorium mother cell walls at the host cell penetration site, haustorial walls, and the extrahaustorial matrix

1986 ◽  
Vol 64 (11) ◽  
pp. 2561-2575 ◽  
Author(s):  
J. Chong ◽  
D. E. Harder ◽  
R. Rohringer
Keyword(s):  
Host Cell ◽  
Mother Cell ◽  
Cell Walls ◽  
Distal Part ◽  
Rust Fungus ◽  
Neck Region ◽  
Cell Penetration ◽  
Wheat Stem Rust ◽  
Reactive Material ◽  
Extrahaustorial Matrix

Various cytochemical tests on the wheat stem rust fungus were used to determine differences in components of the walls of the haustorium mother cell at the host cell penetration site and the haustorial neck and body and to describe some of the chemical properties of the extrahaustorial matrix. There were two transition zones with respect to wall composition. The first was at the host cell penetration site; chitin, present in haustorium mother cell walls, was not detected in haustorial neck walls. The second transition zone was at the neck ring; compared with walls of the proximal neck region, those distal to the neck ring contained more protein and lost much of their periodate – thiocarbohydrazide – silver proteinate reactive material and all concanavalin A binding material after treatment with protease. The two wall layers of the distal part of the haustorial neck were continuous with those of the haustorium; the wall layers of young haustorial bodies shared their staining properties and lectin affinities with those of the distal part of the haustorial necks, reflecting their common origin. As the haustoria matured, their body walls bound wheat germ lectin, but the neck walls did not. Tests indicated that polysaccharide and glycoprotein were present in the extrahaustorial matrix.

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.

Ultrastructure of the early stages of infection of peanut leaves by the rust fungus Puccinia arachidis

1989 ◽  
Vol 67 (12) ◽  
pp. 3570-3579 ◽  
Author(s):  
C. W. Mims ◽  
J. Taylor ◽  
E. A. Richardson
Keyword(s):  
Host Cell ◽  
Mother Cell ◽  
Primary Infection ◽  
Rust Fungus ◽  
Mitotic Division ◽  
Infection Process ◽  
Rust Disease ◽  
Puccinia Arachidis ◽  
Mother Cells ◽  
Infection Hypha

Peanut rust disease proved to be an excellent system for ultrastructural study of development of infection structures by the fungus Puccinia arachidis. Fungal structures were clearly visible by light microscopy in fixed and embedded samples and could be located either on leaf surfaces or within the large substomatal chambers of peanut leaves. Samples could easily be oriented for thin sectioning. The infection process was a highly orchestrated process involving precisely timed events and highly specialized structures. Infection pegs developed from appressoria over stomata and entered the leaf by growing into the openings between guard cells. Once past the rim formed by the guard cell walls, the infection peg expanded to form a substomatal vesicle in which a synchronous mitotic division of the four nuclei occurred. A primary infection hypha then developed from the vesicle and grew into the mesophyll of the leaf until its tip or side contacted a host cell. A septum then delimited a binucleate or trinucleate terminal haustorial mother cell from the remainder of the infection hypha. The wall of the haustorial mother cell became closely appressed to that of the host cell. Following differentiation of the haustorial mother cell, a penetration peg arose from it and penetrated the host cell wall. The peg invaginated the host cell plasma membrane as it elongated and then expanded at its tip to form the haustorium body into which most of the contents of the haustorial mother cell moved. Meanwhile, the primary infection hypha formed secondary hyphae that gave rise to additional haustorial mother cells and haustoria. Key words: Puccinia arachidis, peanut rust, infection process, ultrastructure.

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.

Ultrastructure of teliospore germination and basidiospore formation in the rust fungus Gymnosporangium clavipes

1981 ◽  
Vol 59 (6) ◽  
pp. 1041-1049 ◽  
Author(s):  
Charles W. Mims
Keyword(s):  
Lipid Droplets ◽  
Germ Tube ◽  
Rust Fungus ◽  
Spore Wall ◽  
Pore Region ◽  
Synaptonemal Complexes ◽  
Germ Pore ◽  
Teliospore Germination ◽  
Cytoplasmic Vesicles ◽  
Prophase Nucleus

A mature teliospore of Gymnosporangium clavipes is two celled with a long pedicel. The spore wall appears multilayered and a germ pore region is present in the wall at each end of the teliospore. The cytoplasm of the spore is dense and packed with lipid droplets. A single, dense, prophase nucleus is present in each cell. Synaptonemal complexes were observed in younger spores but not in mature, germinable spores. The cytoplasm of a germinating spore appears less dense than that of a nongerminating spore. During germination a germ tube emerges from the germ pore region of each cell. Cytoplasmic vesicles are numerous in the tip of the rapidly elongating promycelium. The nucleus enters the promycelium and divides meiotically. Centripetally developing septa divide the promycelium into four uninucleate cells each of which gives rise to a sterigma at the tip of which a basidiospore initial develops. Cytoplasmic vesicles are prominent in the tip of the developing sterigma and in the basidiospore initial. Once the nucleus has entered the basidiospore initial it divides mitotically. During this time time a septum develops within the sterigma and the spore is delimited from the sterigma by the formation of a second septum at the base of the spore.

Ultrastructure of spermatia and spermatium ontogeny in the rust fungus Cronartium quercuum f.sp. fusiforme

1996 ◽  
Vol 74 (7) ◽  
pp. 1050-1057 ◽  
Author(s):  
C. W. Mims ◽  
R. L. Doudrick
Keyword(s):  
Morphological Changes ◽  
Rust Fungus ◽  
Thin Wall ◽  
Sporogenous Cell ◽  
Large Nucleus ◽  
Cronartium Quercuum ◽  
Transmission Electron ◽  
Large Numbers ◽  
Pine Seedlings ◽  
Fungal Tissue

Spermogonia of Cronartium quercuum f.sp. fusiforme developed just beneath the bark on galled regions of infected pine seedlings. Spermogonia consist of flattened, spreading, island-like masses of fungal tissue covered with a thin layer of liquid containing large numbers of spermatia. Spermatia arose in an annellophoric fashion from the tips of long, slender sporogenous cells produced in a distinct layer. Each sporogenous cell contained a large prominent nucleus that underwent mitosis as each spermatium initial developed. One of the resulting nuclei moved into the initial while the other remained in the sporogenous cell. Once a spermatium was delimited, it was pushed away from the tip of the sporogenous cell as another spermatium initial developed below it. Once delimited, a spermatium underwent specific morphological changes as it matured. A mature spermatium was subpyriform in shape and surrounded by a thin wall. In addition to a single large nucleus each spermatium contained ribosomes, mitochondria, lipid bodies, strands of endoplasmic reticulum, vacuole-like inclusions, and many small vesicles that packed its base. Keywords: transmission electron microscopy, pycnidia, pycnidiospores, spermogonia.

Megasporogenesis and megagametogenesis in Pelargonium × hortorum

1973 ◽  
Vol 51 (3) ◽  
pp. 607-612 ◽  
Author(s):  
Annie H. Tsai ◽  
Patricia M. Harney ◽  
R. L. Peterson
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Outer Integument ◽  
Embryo Sac ◽  
Mature Embryo ◽  
Polar Nucleus ◽  
Archesporial Cell ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Cell Functions

The ovary of Pelargonium × hortorum contains five pairs of superposed ovules in five locules. These ovules are bitegmic and crassinucellar and the upper ovule of each pair is campylotropous while the lower one is anatropous. A single archesporial cell functions directly as the megaspore mother cell. Meiotic division of the megaspore mother cell results in the formation of a linear tetrad of megaspores of which the chalazal megaspore is functional. Embryo sac development is of the polygonum type. Rapid degeneration of the three antipodals occurs followed by the fusion of the two polar nuclei. Therefore, the mature embryo sac contains the egg, the two synergids, and the fused polar nucleus. Double fertilization takes place. Ninety-two percent of the fertilized ovules of P. × hortorum cv. ‘Purple Heart’ are found in the upper position.The two integuments are initiated before the differentiation of the archesporial cell. Cells of the outer layer of the outer integument and the inner layer of the inner integument deposit tannins. The nucellus develops through divisions of the parietal cells of the nucellar epidermal cells.

Cytochemical studies on Puccinia graminis f. sp. tritici in a compatible wheat host. I. Walls of intercellular hyphal cells and haustorium mother cells

1985 ◽  
Vol 63 (10) ◽  
pp. 1713-1724 ◽  
Author(s):  
J. Chong ◽  
D. E. Harder ◽  
R. Rohringer
Keyword(s):  
Concanavalin A ◽  
Mother Cell ◽  
Cell Walls ◽  
Lectin Binding ◽  
Rust Fungus ◽  
Hydroxyl Groups ◽  
Protease Treatment ◽  
Wheat Leaves ◽  
Formed Part ◽  
Mother Cells

Walls of intercellular hyphae and haustorium mother cells of the stem rust fungus in wheat leaves were studied cytochemically using lectin probes, periodate – thiocarbohydrazide – silver proteinate or periodate–chromate–phosphotungstate staining, and protease treatment. Up to six possible layers in the haustorium mother cell walls and four in the hyphal walls were resolved. Three outer layers of the haustorium mother cell walls were continuous with the three outer layers of the hyphal walls. The two innermost layers of the haustorium mother cell walls were not continuous with the hyphal walls but formed part of the septum. These two layers differed from the other layers of the haustorium mother cell walls in having no affinity to concanavalin A. In both hyphal and haustorium mother cell walls, components with an affinity for concanavalin A were extractable with protease treatment. Wheat-germ lectin binding occurred throughout the fungal walls except in the two outermost layers. Periodate-sensitive glycosubstances were also common, but the amounts varied among layers. Although some of these glycosubstances were confirmed as polysaccharides containing sugars with vicinal hydroxyl groups, much of the glycosubstances present in the walls was sensitive to protease treatment, indicating a possible glycoprotein composition.

An ultrastructural comparison of monokaryotic and dikaryotic haustoria formed by the fusiform rust fungus Cronartium quercuum f.sp. fusiforme

1982 ◽  
Vol 60 (12) ◽  
pp. 2914-2922 ◽  
Author(s):  
D. J. Gray ◽  
H. V. Amerson ◽  
C. G. Van Dyke
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Pinus Taeda ◽  
Mother Cell ◽  
Rust Fungus ◽  
Neck Region ◽  
Cronartium Quercuum ◽  
Host Cell Wall ◽  
Mother Cells ◽  
Mother Cell Wall

Haustoria formed by the monokaryotic stage of Cronartium quercuum f. sp. fusiforme in Pinus taeda differed from those of the dikaryotic phase in Quercus rubra. Monokaryotic (M) haustorial walls were continuous with the walls of relatively undifferentiated haustorial mother cells. The septate M-haustorial neck and expanded M-haustorial body were separated from the invaginated host plasmalemma by a sheath which was continuous with the host cell wall. Collars encasing sheaths were infrequently observed. Dikaryotic (D) haustoria were morphologically similar to M-haustoria; however, they differed in several respects when examined with TEM. The D-haustorial mother cell wall was thickened at the penetration site but a reduction in the number of wall layers occurred between the thickened portion of the mother cell and the D-haustorium. A darkly staining neckband was present in the wall of the nonseptate D-haustorial neck but was lacking in the M-haustorium. An extensive sheath separated the invaginated host plasmalemma from the D-haustorial wall distally from the neckband. However, the sheath was separated from the D-haustorial wall and from the host cell wall by an invaginated host plasmalemma doubled in the haustorial neck region proximally from the neckband.

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