Structural studies of the development of infection structures of cowpea rust, Uromyces phaseoli var. vignae. II. Vacuoles.

1979 ◽  
Vol 57 (17) ◽  
pp. 1830-1837 ◽  
Author(s):  
I. Brent Heath ◽  
Michèle C. Heath
Keyword(s):  
Control System ◽  
Structural Studies ◽  
Developmental Pathway ◽  
Infection Structures ◽  
Uromyces Phaseoli ◽  
Mother Cells ◽  
Germ Tubes

During development of infection structures of cowpea rust, Uromyces phaseoli var. vignae, migration of cytoplasm from one structure to the next is accompanied by production of vacuoles. The developmental pathway of these vacuoles appears to differ in different sites of production. In germinating uredospores, appressoria, and substomatal vesicles, their development includes the formation and enlargement of electron-opaque globule-containing vesicles, termed vacuole precursor vesicles (VPVs). In contrast, in the elongating germ tubes and vacuolating haustorial mother cells, VPVs do not appear during vacuolation. During development of VPVs into vacuoles there seems to be a control system which selectively activates only a portion of the VPV population.

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.

THE CYTOLOGY OF INFECTION STRUCTURE DEVELOPMENT IN UREDIOSPORE GERM TUBES OF UROMYCES PHASEOLI VAR. TYPICA (PERS.) WINT.

1967 ◽  
Vol 45 (4) ◽  
pp. 447-450 ◽  
Author(s):  
Ramesh Maheshwari ◽  
A. C. Hildebrandt ◽  
P. J. Allen
Keyword(s):  
Nuclear Division ◽  
In Vitro Differentiation ◽  
Structure Development ◽  
Infection Structures ◽  
Uromyces Phaseoli ◽  
Mother Cells ◽  
Germ Tubes ◽  
Infection Hypha ◽  
Feulgen Technique

Urediospores of Uromyces phaseoli var. typica (Pers.) Wint. race 32 Arth. germinated on mineral oil – nitrocellulose membranes and sequentially developed appressoria, vesicles, and infection hyphae. The nuclear behavior during in vitro differentiation of infection structures was studied by use of the Feulgen technique. The two urediospore nuclei divided in the germ tube before the formation of appressorium. This was followed by a second division of the four daughter nuclei in the appressorium, and occasionally by a third division of the eight nuclei in the vesicle and infection hypha. Haustorial mother cells were formed in infection hyphae in vitro and contained from two to five nuclei. In contrast, nuclear division did not occur in germ tubes where growth continued linearly. Infection structures that developed in vitro resembled those produced during infection of the host by urediospores of other species of rust fungi.

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.

Variation of mycelial morphology between species and formae spéciales of rust fungi of cereals and grasses

1986 ◽  
Vol 64 (12) ◽  
pp. 2976-2983 ◽  
Author(s):  
R. E. Niks
Keyword(s):  
Host Species ◽  
Primary Infection ◽  
Rust Fungi ◽  
Species Level ◽  
Puccinia Coronata ◽  
Mycelial Morphology ◽  
Infection Structures ◽  
Interspecific Differences ◽  
Mother Cells ◽  
Taxonomic Studies

The morphology of the infection structures (substomatal vesicles, primary infection hyphae, and haustorial mother cells) was described for 23 isolates comprising nine rust species of cereals and grasses. Interspecific differences in morphology were very large. The results indicate that it should be possible to identify single sporelings at least to species level. Between samples of the same rust species collected from different host species, no qualitative differences were found in some cases (Puccinia coronata); in other cases the differences between samples were as large as between species (P. recondita, P. brachypodii). Because primary infection structures develop on virtually any graminaceous plant, all observations were done using barley or Triticum dicoccum seedlings as substrate. The results indicate that inclusion of mycelial morphology in description of rust taxa may be helpful in taxonomic studies. The differences in mycelial morphology may also be exploited in certain phytopathological studies.

scholarly journals Infection of Cranberry Flowers by Monilinia oxycocci and Evaluation of Cultivars for Resistance to Cottonball

1999 ◽  
Vol 89 (12) ◽  
pp. 1127-1130 ◽  
Author(s):  
P. S. McManus ◽  
V. M. Best ◽  
R. P. Voland
Keyword(s):  
Low Level ◽  
Infection Structures ◽  
Histological Method ◽  
Nucellar Tissue ◽  
Germ Tubes ◽  
Term Management ◽  
Greenhouse Tests

Infection of cranberry flowers by conidia of Monilinia oxycocci, the cottonball pathogen, was investigated using a squash-mount histological method. Conidia germinated on anthers, nectaries, petals, and stigmata, but not styles. The stigma was the only flower part penetrated by the fungus, but no specialized infection structures were noted. Both fungal and pollen germ tubes grew through the stylar canal and made contact with ovules and nucellar tissue by 72 h after inoculation and pollination. Cottonball incidence was greatest when stigmata were inoculated; the low level of cottonball that resulted from inoculation of other flower parts and in noninoculated flowers was attributed to contamination of stigmata. In greenhouse tests, cottonball incidence was 25, 28, 31, and 38% for cvs. Searles, Pilgrim, Ben Lear, and Stevens, respectively, and was greater for M. oxycocci isolate 593 than isolate 591. We conclude that the stigma is the sole floral infection court for conidia of M. oxycocci and that the most popular cranberry cultivars in Wisconsin do not differ in inherent resistance to cottonball. The relevance of these findings to the long-term management of cottonball is discussed.

Morphology, histochemistry, and germination of conidia of Sporidesmium sclerotivorum

1989 ◽  
Vol 67 (2) ◽  
pp. 313-317 ◽  
Author(s):  
Suzanne Bullock ◽  
H. J. Willetts ◽  
P. B. Adams
Keyword(s):  
Phenolic Compounds ◽  
Infection Structures ◽  
Asexual Spore ◽  
Spore Walls ◽  
Germ Tubes ◽  
Distal Cell

Sporidesmium sclerotivorum, a mycoparasite of sclerotia of Sclerotinia spp., produces two types of asexual spore, macroconidia and microconidia of the Selenosporella type. Macroconidia developed by dilation of the conidiophore apex, which then divided to form up to eight cells. The outer layers of the thick spore walls were heavily pigmented and contained phenolic compounds. The cytoplasm of mature spores contained polysaccharides and proteins but there were no specialized storage bodies. Germ tubes emerged through a pore in the wall of the distal cell of the macroconidia. They grew over the surface of host sclerotia and entered between rind cells without formation of specialized infection structures. Microconidia of the Selenosporella state of S. sclerotivorum formed on simple or branched conidiophores. Sympodial conidiogenous cells bearing the microconidia were arranged in a verticil at the tips of these conidiophores.

scholarly journals Infection processes of Ciborinia camelliae on camellia flower tissue

2000 ◽  
Vol 53 ◽  
pp. 151-156 ◽  
Author(s):  
V. Vingnana-Singam ◽  
P.G. Long ◽  
R.E. Rowland
Keyword(s):  
Confocal Microscopy ◽  
Host Cell ◽  
Cell Walls ◽  
Trypan Blue ◽  
Infection Process ◽  
Infection Structures ◽  
Flower Tissue ◽  
Infection Processes ◽  
Germ Tubes

The infection process of Ciborinia camelliae the cause of camellia flower blight was studied using light and confocal microscopy Germination and infection structures of the pathogen on petals were stained with trypan blue in lactophenol and with glutaraldehyde for light and confocal microscopy respectively Within 6 h of inoculation the ascospores germinated and formed short germ tubes The host cuticle was penetrated and within a further 6 to 18 h a large swollen structure formed underneath each penetration From here a hypha grew under the cuticle to the junction between two cells and then developed as intercellular hyphae The mycelium continues to develop intercellularly for the next 72 h but without causing extensive destruction of the host cell walls

scholarly journals Ultrastructural and Immunochemical Changes During the In Vitro Development of Plasmopara halstedii

2003 ◽  
Vol 93 (8) ◽  
pp. 1023-1030 ◽  
Author(s):  
Sandrine Bouterige ◽  
Guy Tronchin ◽  
Maurice Lesourd ◽  
Agnès Marot-Leblond ◽  
Valérie Molinéro ◽  
...  
Keyword(s):  
Ultrastructural Changes ◽  
Asexual Development ◽  
Direct Examination ◽  
Plasmopara Halstedii ◽  
In Vitro Development ◽  
A Cell ◽  
Mother Cells ◽  
Vitro Development ◽  
Germ Tubes

The asexual phase of the life cycle of Plasmopara halstedii, the causal agent of downy mildew of sunflower, plays a key role in the propagation of the disease. We investigated the morphological and ultrastructural changes that occur during the asexual development of the pathogen. Direct examination of infected cotyledons confirmed the presence of sporangiophores. In contact with water, important ultrastructural changes occurred, affecting the surface of zoosporangia, which became smoother, and their cytoplasm, which differentiated into flagellate zoospores. The subsequent encystment of zoospores was characterized by the synthesis of a cell wall and the loss of the flagella. In addition, two monoclonal antibodies (MAbs) specific for P. halstedii were used to analyze the immunochemical changes associated with these modifications. MAb 16A6, which bound to a 48-kDa glycoprotein, mainly labeled the surface of mobile or encysted zoospores and of mother cells of germ tubes. Conversely, MAb 2F9, which recognized highly glycosylated antigens, labeled the surface of zoosporangia and of flagellate zoospores, but not the encysted zoospores. These results provide new insights into the morphological and ultrastructural changes associated with the release and the encystment of zoospores which may be interesting targets for the development of new antimicrobial products.

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.

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