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.

STUDIES ON THE NATURE OF RUST RESISTANCE IN WHEAT: VI. EFFECT OF HYDROGEN ION CONCENTRATION, PHENOLIC COMPOUNDS, AND HOST EXTRACTS ON THE GERMINATION OF UREDINIOSPORES OF PUCCINIA GRAMINIS TRITICI, FORM 21

1934 ◽  
Vol 11 (6) ◽  
pp. 667-686 ◽  
Author(s):  
J. Ansel Anderson
Keyword(s):  
Phenolic Compounds ◽  
Rust Resistance ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Puccinia Graminis ◽  
Inhibitory Effects ◽  
Hydrogen Ion Concentration ◽  
Puccinia Graminis Tritici ◽  
The Press ◽  
Germ Tubes

Urediniospores of Puccinia graminis tritici, form 21, were sown on buffer solutions covering the range from pH 3 to pH 8. Maximum germination was obtained between pH 5.8 and 6.5, with indications that if the point of maximum germination could be determined with precision it would be found to lie in the neighborhood of pH 6.2.The effect of buffered and unbuffered solutions of pure phenolic compounds on the germination of urediniospores was studied. Greater inhibition was obtained with unbuffered solutions owing to the additional effect of hydrogen ion concentration. In buffered solutions, at pH 6.0, germination was prevented by 45 p.p.m. of hydroquinone, 125 of o-cresol, 180 of anisic acid, 250 of benzoic acid, 340 of catechol, 400 of guaiacol and 600 of phenol. A number of other compounds were also studied. The inhibitory effects of compounds, of which the bactericidal effects are known, are fairly closely related to their bactericidal efficiency.Investigations were made of the inhibitory effects on spore germination and the growth of germ tubes, of aqueous dilutions of 15, 10, 5 and 2.5% of the press-juice of Vernal, Khapli, Marquis and Little Club wheats. Statistical treatment of the data accumulated in ten series of determinations, in which a total of 160,000 spores was counted, showed that significant differences occurred between varieties and that variations in the total solid content and hydrogen ion concentration of the press-juice had no consistent effect upon the results. Although the results were not entirely clear-cut, it is concluded that the varieties fall in the following order with respect to increasing inhibitory effect of their extracts: Vernal, Marquis, Khapli and Little Club. Since Vernal and Khapli are resistant to form 21 whereas Marquis and Little Club are susceptible, the results fail to show any relationship between the effects of host extracts on the germination of urediniospores, or on the growth of germ tubes, and the rust resistance of the variety.

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 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.

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.

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.

Structure and cytochemistry of the walls of urediospores, germ tubes, and appressoria of Puccinia graminis tritici

1986 ◽  
Vol 64 (3) ◽  
pp. 476-485 ◽  
Author(s):  
D. E. Harder ◽  
J. Chong ◽  
R. Rohringer ◽  
W. K. Kim
Keyword(s):  
Concanavalin A ◽  
Outer Layer ◽  
Wheat Germ ◽  
Germ Tube ◽  
Lectin Binding ◽  
Periodic Acid ◽  
Puccinia Graminis ◽  
Spore Walls ◽  
Germ Tubes ◽  
Wheat Germ Lectin

Several cytochemical methods demonstrated that urediospore walls of Puccinia graminis f. sp. tritici were probably composed of five layers, including the pellicle as the outermost layer. Two previously undescribed layers were located around the inner periphery of the spore walls. Staining for periodate-sensitive glycosubstances occurred uniformly and heavily throughout the wall except that the pellicle was unstained, and the innermost layer (3c) was more lightly stained by periodic acid – thiocarbohydrazide – silver proteinate. There was little wheat germ lectin or concanavalin A binding to the urediospore wall except in the hilar region, where wheat germ lectin bound heavily, and in the germ pore region, where binding of concanavalin A occurred. The walls of about one-half of the urediospores that were examined contained silicon deposits. Germ tube walls were composed of two layers: a broad outer layer and a narrower inner layer. The inner layer stained more heavily for periodate-sensitive glycosubstances than did the outer layer. Germ tube walls bound wheat germ lectin, but not concanavalin A. Appressorial walls were also composed of two layers, but the inner layer was much broader than that of germ tube walls, and the outer layer stained more heavily for periodate-sensitive glycosubstances. There was strong wheat germ lectin binding to the appressorial walls, but concanavalin A binding was sparse. Both germ tubes and appressoria were coated with a mucilagenouslike substance.

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

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.

ELECTRON MICROSCOPY OF UREDOSPORES OF MELAMPSORA LINI AND OF RUST-INFECTED FLAX

1967 ◽  
Vol 45 (9) ◽  
pp. 1575-1582 ◽  
Author(s):  
M. S. Manocha ◽  
Michael Shaw
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Linum Usitatissimum ◽  
Room Temperature ◽  
Rust Fungus ◽  
Thin Sections ◽  
Infection Structures ◽  
Linum Usitatissimum L ◽  
Melampsora Lini ◽  
Germ Tubes

Thin sections of germinated and ungerminated uredospores of the flax rust fungus (Melampsora lini (Pers.) Lev.) and rust-infected cotyledons of flax (Linum usitatissimum L., variety Bison) were examined in a Philips 100B electron microscope. The line structure of the mature uredospores, the formation of germ tubes including the development of cross walls, and of the intercellular mycelium, haustoria, sporogenous hyphae, and developing uredospores are all briefly described. Germinated and ungerminated uredospores were fixed in KMnO4 followed by OsO4 at room temperature. Infected tissue was fixed in KMnO4 at room temperature or in glutaraldehyde at 4 °C followed by OsO4 at 4 °C. Nucleoli were not observed in the nuclei of mature uredospores or germ tubes but were present in the intercellular mycelium, sporogenous hyphae, and developing uredospores and were particularly prominent in the two haustorial nuclei. The results are discussed and attention is drawn to the need for further work on the nuclei and nucleoli in germinating uredospores under conditions conducive to the development of infection structures.

Sign in / Sign up

Export Citation Format

Share Document