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.

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.

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.

scholarly journals Transfer of label from 3H-glucose in Digitaria eriantha leaves to the rust fungus Puccinia digitariae Pole Evans.

1985 ◽  
Vol 33 (8) ◽  
pp. 809-812 ◽  
Author(s):  
M E Rey ◽  
H M Garnett
Keyword(s):  
Primary Infection ◽  
Secondary Infection ◽  
Rust Fungus ◽  
Infection Process ◽  
Bremia Lactucae ◽  
Infection Structures ◽  
Obligate Parasites ◽  
Digitaria Eriantha ◽  
Germ Tubes

Digitaria eriantha pentzii was fed 3H-glucose prior to inoculation with uredospores of Puccinia digitariae Pole Evans. Twenty-one hours after inoculation, uptake of label from 3H-glucose by the primary infection structures of P. digitariae was demonstrated employing autoradiography. These results indicate that an exchange of nutrients between host and pathogen occurs very early on in the infection process, during the formation of the primary infection structures. Despite contrary reports that obligate parasites receive no nutrition before establishment of haustoria, this study supports the work of Andrews (Can J Bot 53:1103, 1975), who demonstrated uptake of 3H-glucose label from lettuce cotyledons into the primary and secondary infection vesicles, appressoria, and germ tubes of Bremia lactucae.

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.

scholarly journals Melampsora larici-populina Transcript Profiling During Germination and Timecourse Infection of Poplar Leaves Reveals Dynamic Expression Patterns Associated with Virulence and Biotrophy

2011 ◽  
Vol 24 (7) ◽  
pp. 808-818 ◽  
Author(s):  
Sébastien Duplessis ◽  
Stéphane Hacquard ◽  
Christine Delaruelle ◽  
Emilie Tisserant ◽  
Pascal Frey ◽  
...  
Keyword(s):  
Rust Fungus ◽  
Expression Patterns ◽  
Infection Process ◽  
Plant Colonization ◽  
In Planta ◽  
Rust Disease ◽  
Dynamic Expression ◽  
Transcript Profiles ◽  
Rust Pathogens ◽  
Poplar Leaves

Melampsora larici-populina is responsible for poplar leaf rust disease and causes severe epidemics in poplar plantations in Europe. The poplar rust genome has been recently sequenced and, in order to find the genetic determinants associated with its biotrophic lifestyle, we generated a whole-genome custom oligoarray and analyzed transcript profiles of M. larici-populina during the infection timecourse in poplar leaves. Different stages were investigated during the asexual development of the rust fungus, including resting and germinating urediniospores and seven in planta stages in the telial host. In total, 76% of the transcripts were detected during leaf infection as well as in urediniospores, whereas 20% were only detected in planta, including several transporters and many small secreted proteins (SSP). We focused our analysis on gene categories known to be related to plant colonization and biotrophic growth in rust pathogens, such as SSP, carbohydrate active enzymes (CAZymes), transporters, lipases, and proteases. Distinct sets of SSP transcripts were expressed all along the infection process, suggesting highly dynamic expression of candidate rust effectors. In contrast, transcripts encoding transporters and proteases were mostly expressed after 48 h postinoculation, when numerous haustoria are already formed in the leaf mesophyll until uredinia formation, supporting their role in nutrient acquisition during biotrophic growth. Finally, CAZymes and lipase transcripts were predominantly expressed at late stages of infection, highlighting their importance during sporulation.

Structural studies of the development of infection structures of cowpea rust, Uromyces phaseoli var. vignae. I. Nucleoli and nuclei

1978 ◽  
Vol 56 (6) ◽  
pp. 648-661 ◽  
Author(s):  
Michèle C. Heath ◽  
I. Brent Heath
Keyword(s):  
Mother Cell ◽  
Cell Formation ◽  
Structural Studies ◽  
Nucleolar Activity ◽  
Infection Structures ◽  
Uromyces Phaseoli ◽  
Living Material ◽  
Mother Cells ◽  
Germ Tubes ◽  
Infection Hypha

Light microscopical observations of living germ tubes and infection structures of cowpea rust were combined with an ultrastructural study to show that a nucleolus was present in the interphase nucleus at all stages of development from uredospore germination through to new uredospore formation. Vacuolate nucleoli were common in germ tubes but only nonvacuolate nucleoli were observed at other stages of fungal development. When grown on oil-containing collodion membranes, germinating uredospores, germ tubes, appressoria, and infection hyphae without haustorial mother cells all contained nucleoli composed primarily of nongranular material. Predominantly granular nucleoli were observed in developing uredospores and all parasitic stages in the leaf after the formation of the first haustorial mother cell. However, the fact that granular nucleoli were also seen in a membrane-grown infection hypha after haustorial mother cell formation suggested that the host was not required to stimulate the resumption of nucleolar activity. Electron-opaque patches, presumed to be condensed chromatin, were most prominent in the nucleoplasm of haustorial mother cells and virtually absent in germinating uredospores and germ tubes. The significance of this observation is discussed. A reduction in nuclear volume was observed in living material prior to cytokinesis in the appressorium and the substomatal vesicle. Evidence suggested that this reduction was produced by the expulsion of part of the nucleoplasm, plus the nucleolus, during mitosis rather than before as suggested for other rusts. Nuclei of haustorial mother cells and haustoria were also smaller than those in intercellular hyphae but the mechanism by which this was achieved could not be determined.

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.

Fungal development and host cell responses to the rust fungus Puccinia substriata var. indica in seedling and mature leaves of susceptible and resistant pearl millet

1991 ◽  
Vol 69 (6) ◽  
pp. 1207-1219 ◽  
Author(s):  
J. Taylor ◽  
C. W. Mims
Keyword(s):  
Host Cell ◽  
Pearl Millet ◽  
Rust Fungus ◽  
Plant Cells ◽  
Host Cells ◽  
Resistant Cultivar ◽  
Fungal Colonization ◽  
Mature Leaves ◽  
Before And After ◽  
Mother Cells

The rust fungus Puccinia substriata var. indica established a compatible relationship with host cells, characterized by large numbers of haustoria and an extensive system of intercellular hyphae, in seedling leaves of the susceptible pearl millet cultivar Tift 23DB. At some infection sites, however, necrotic host cells and papillae formed by plant cells adjacent to infection hyphae or haustorial mother cells were noted. In seedling leaves of the moderately resistant cultivar 86-8770, the initial interaction between host cells and the pathogen was quite variable and included successful haustorium formation as well as papilla deposition. Necrosis of host cells apparently developed as a gradual disorganization of the cytoplasm of invaded and surrounding host cells and occurred at all infection sites by 2 days postinoculation. In seedling leaves of the highly resistant cultivar Tift 85DB, haustoria were established at early stages of development, followed by a rapid necrosis response at 1 day postinoculation. Host cell disintegration was noted both before and after abnormalities in haustoria were observed. In mature leaves of all three cultivars, wall deposits were quite extensive at 12 h postinoculation. In addition, necrotic plant cells appeared rapidly in both susceptible and resistant cultivars. Both of these factors may have contributed to the increased resistance to fungal colonization observed in mature leaves. Key words: Puccinia substriata var. indica, pearl millet rust, host resistance, ultrastructure.

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.

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