Substrate surface influences upon germination of Colletotrichum truncatum conidia

1994 ◽  
Vol 72 (12) ◽  
pp. 1758-1765 ◽  
Author(s):  
G. H. Egley
Keyword(s):  
Germ Tube ◽  
Substrate Surface ◽  
Cellulose Nitrate ◽  
Colletotrichum Truncatum ◽  
Glass Cover ◽  
Solid Substrates ◽  
Appressoria Formation ◽  
Germ Tubes ◽  
Cellulose Nitrate Filter ◽  
Good Germination

Substrates influenced germination of conidia of the mycoherbicide, Colletotrichum truncatum. Very few (< 10%) conidia germinated when incubated while suspended in water or when incubated on or in partially liquefied agar. Many (> 70%) were induced to germinate when incubated on firm agar. The percentage of germinated conidia increased as agar firmness increased. Not all solid substrates equally influenced germination. Over 50% of the conidia germinated on chromatography paper, cellulose acetate filter, or on hard (plastic cover slip) substrates. In contrast, germination was relatively poor on cellulose nitrate filter and glass cover slips. Some natural substrates of dissimilar texture (wood, live plant leaf) produced good germination. Lower O2 levels or limited gas exchange for submerged conidia did not prevent germination because many conidia germinated while submerged on or between firm substrates. Subjecting conidia to motion during incubation between glass cover slips favored germ tube production rather than appressoria formation. Evidence suggests a positive germination response of C. truncatum conidia to solid substrates that occurs prior to the well-documented thigmotropic response of germ tubes of germinated conidia. Key words: Colletotrichum truncatum, conidia germination, thigmotropism, substrate.

Ultrastructure of conidia, conidium germination, and appressorium development in the plant pathogenic fungus Colletotrichum truncatum

1991 ◽  
Vol 69 (11) ◽  
pp. 2455-2467 ◽  
Author(s):  
C. Gerald Van Dyke ◽  
Charles W. Mims
Keyword(s):  
Germ Tube ◽  
Pathogenic Fungus ◽  
Freeze Substitution ◽  
Colletotrichum Truncatum ◽  
Dialysis Membrane ◽  
The Matrix ◽  
Single Nucleus ◽  
Conidium Germination ◽  
Matrix Spread ◽  
Germ Tubes

Nongerminating conidia of Colletotrichum truncatum were coated with copious amounts of a finely fibrillar extracellular matrix. This matrix spread out onto the dialysis membrane used as a substrate in this study. Each thin-walled conidium contained a single nucleus that underwent mitosis 1–2 h following placement of aqueous suspensions of conidia on membranes. A septum subsequently developed near the middle of the conidium, creating two uninucleate cells. Just prior to or during septum development a germ tube emerged laterally, usually near one end of the conidium. The nucleus moved into the germ tube and underwent mitosis. One daughter nucleus remained in the germ tube, the other moved back into the conidium. Developing germ tubes appeared to produce large amounts of electron-dense, fibrillar material that coated their surfaces. This material blended into the remnants of the matrix initially coating conidia and could not be clearly differentiated from the latter material. Germ tubes grew to various lengths before forming appressoria. Appressorium differentiation began shortly after the germ-tube tip curved sharply. A septum developed to delimit the tip that differentiated into a swollen appressorium. By 6 h following initial hydration of conidia, appressoria were melanized and the surrounding extracellular material had condensed onto their surfaces, forming an electron-dense coating that appeared to stick appressoria to dialysis membranes. A tiny penetration peg developed from an apparently wall-less region on the underside of the mature appressorium and, in some instances, grew a short distance into the dialysis membrane. Key words: electron microscopy, freeze substitution, conidia, appressoria.

Morphology and lipid body and vacuole dynamics during secondary conidia formation inColletotrichum acutatum: laser scanning confocal analysis

2006 ◽  
Vol 52 (2) ◽  
pp. 117-124 ◽  
Author(s):  
Ariani Corrêa Barbosa ◽  
Anousca Evelyn do Carmo ◽  
Letícia Graf ◽  
Roberto Tomaz ◽  
Caroline Fogaça de Souza ◽  
...  
Keyword(s):  
Mycelial Growth ◽  
Laser Scanning ◽  
Germ Tube ◽  
Lipid Body ◽  
Colletotrichum Acutatum ◽  
Lipid Bodies ◽  
Acidic Vesicles ◽  
Appressoria Formation ◽  
Germ Tubes ◽  
Exogenous Nutrients

Colletotrichum acutatum may develop one or more secondary conidia after conidial germination and before mycelial growth. Secondary conidia formation and germination were influenced by conidia concentration. Concentrations greater than 1 × 105conidia/mL were associated with germination decrease and with secondary conidia emergence. Secondary conidia can form either alone or simultaneously with germ tubes and appressoria. Confocal analysis showed numerous lipid bodies stored inside ungerminated conidia, which diminished during germ tube and appressoria formation, with or without secondary conidia formation. They were also reduced during secondary conidia formation alone. While there was a decrease inside germinated conidia, lipid bodies appeared inside secondary conidia since the initial stages. Intense vacuolization inside primary germinated conidia occurred at the same time as the decrease in lipid bodies, which were internalized and digested by vacuoles. During these events, small acidic vesicles inside secondary conidia were formed. Considering that the conidia were maintained in distilled water, with no exogenous nutrients, it is clear that ungerminated conidia contain enough stored lipids to form germ tubes, appressoria, and the additional secondary conidia replete with lipid reserves. These results suggested a very complex and well-balanced regulation that makes possible the catabolic and anabolic pathways of these lipid bodies.Key words: secondary conidia, lipid bodies, vacuoles, confocal microscopy, Colletotrichum.

Anastomosis of germ tubes and migration of nuclei in germ tube networks of the soybean rust pathogen, Phakopsora pachyrhizi

2011 ◽  
Vol 132 (2) ◽  
pp. 163-167 ◽  
Author(s):  
R. Vittal ◽  
H. -C. Yang ◽  
G. L. Hartman
Keyword(s):  
Germ Tube ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Rust Pathogen ◽  
And Migration ◽  
Germ Tubes

Ascospore germination, growth in culture, and imperfect spore formation in Cookeina sulcipes and Phillipsia crispata

1975 ◽  
Vol 53 (1) ◽  
pp. 56-61 ◽  
Author(s):  
J. W. Paden
Keyword(s):  
Germ Tube ◽  
Outer Wall ◽  
Wall Layer ◽  
Spore Formation ◽  
Spore Surface ◽  
No Formation ◽  
Ascospore Germination ◽  
Germ Tubes

Ascospores of Cookeina sulcipes germinate by one of two modes: (1) by the production of blastoconidia on sympodially proliferating conidiogenous cells which may arise from any point on the spore surface, and (2) by a thick polar germ tube. No ascospores were seen to germinate both ways. The conidiogenous cells are occasionally modified into narrow hyphae. The blastoconidia germinate readily but are evidently very short-lived. Ascospores of Phillipsia crispata germinate by two polar germ tubes; there is no formation of blastoconidia. In both species the inner ascospore wall separated from an outer wall layer during germination. In culture both C. sulcipes and P. crispata form arthroconidia. The arthroconidia are uninucleate; they germinate readily and reproduce the species when transferred to fresh plates.

Carbon dioxide induces endotrophic germ tube formation in Candida albicans

1990 ◽  
Vol 36 (4) ◽  
pp. 249-253 ◽  
Author(s):  
Ruth C. Mock ◽  
Jordan H. Pollack ◽  
Tadayo Hashimoto
Keyword(s):  
Carbon Dioxide ◽  
Candida Albicans ◽  
Sodium Bicarbonate ◽  
Key Words ◽  
Germ Tube ◽  
Tube Formation ◽  
Chemical Inducers ◽  
Tube Emergence ◽  
Ph Range ◽  
Germ Tubes

Candida albicans formed germ tubes when exposed to air containing 5 to 15% carbon dioxide (CO2). The CO2-mediated germ tube formation occurred optimally at 37 °C in a pH range of 5.5 to 6.5. No germ tubes were produced at 25 °C, even when the optimal concentration of CO2 (10%) was present in the environment. The requirement of CO2 for germ tube formation could be partially substituted by sodium bicarbonate but not by N2. Carbon dioxide was required to be present throughout the entire course of germ tube emergence suggesting that its role is not limited to an initial triggering of morphogenic change. We suggest that carbon dioxide may be a common effector responsible for the germ tube promoting activity of certain chemical inducers for C. albicans. Key words: Candida albican germ tubes, CO2-induced germ tube formation, endotrophic germ tube formation.

scholarly journals Regulation of Pathogenic Spore Germination by CgRac1 in the Fungal Plant Pathogen Colletotrichum gloeosporioides

2011 ◽  
Vol 10 (8) ◽  
pp. 1122-1130 ◽  
Author(s):  
Iris Nesher ◽  
Anna Minz ◽  
Leonie Kokkelink ◽  
Paul Tudzynski ◽  
Amir Sharon
Keyword(s):  
Cell Division ◽  
Plant Pathogen ◽  
Germ Tube ◽  
Colletotrichum Gloeosporioides ◽  
Fluorescent Protein ◽  
Nuclear Division ◽  
Simultaneous Formation ◽  
Content Type ◽  
Germ Tubes

ABSTRACT Colletotrichum gloeosporioides is a facultative plant pathogen: it can live as a saprophyte on dead organic matter or as a pathogen on a host plant. Different patterns of conidial germination have been recognized under saprophytic and pathogenic conditions, which also determine later development. Here we describe the role of CgRac1 in regulating pathogenic germination. The hallmark of pathogenic germination is unilateral formation of a single germ tube following the first cell division. However, transgenic strains expressing a constitutively active CgRac1 (CA-CgRac1) displayed simultaneous formation of two germ tubes, with nuclei continuing to divide in both cells after the first cell division. CA-CgRac1 also caused various other abnormalities, including difficulties in establishing and maintaining cell polarity, reduced conidial and hyphal adhesion, and formation of immature appressoria. Consequently, CA-CgRac1 isolates were completely nonpathogenic. Localization studies with cyan fluorescent protein (CFP)-CgRac1 fusion protein showed that the CgRac1 protein is abundant in conidia and in hyphal tips. Although the CFP signal was equally distributed in both cells of a germinating conidium, reactive oxygen species accumulated only in the cell that produced a germ tube, indicating that CgRac1 was active only in the germinating cell. Collectively, our results show that CgRac1 is a major regulator of asymmetric development and that it is involved in the regulation of both morphogenesis and nuclear division. Modification of CgRac1 activity disrupts the morphogenetic program and prevents fungal infection.

Emergence of the aeciospore germ tubes of Cronartium coleosporioides (=Peridermium stalactiforme) as observed by scanning electron microscope

1970 ◽  
Vol 48 (9) ◽  
pp. 1692-1692 ◽  
Author(s):  
Y. Hiratsuka
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Germ Tube ◽  
Germ Tubes ◽  
Scanning Electron

Germ tubes of Cronartium coleosporioides Arth. (= Peridermium stalactiforme Arth. and Kern) emerged between processes through short irregular slits. Germ tube walls were folded when they emerged and expanded after the emergence.

Behavior of Fusarium roseum 'Sambucinum' under carbon starvation conditions in relation to survival in soil

1969 ◽  
Vol 15 (1) ◽  
pp. 117-126 ◽  
Author(s):  
G. J. Griffin ◽  
T. Pass
Keyword(s):  
Latent Period ◽  
Direct Observation ◽  
Germ Tube ◽  
Carbon Starvation ◽  
Glucose Medium ◽  
Glucose Depletion ◽  
High Germination ◽  
Germ Tubes ◽  
Starvation Conditions ◽  
Exogenous Source

Direct observation of washed macroconidia of F. roseum 'Sambucinum' infested in rewetted soil and incubated at 6 °C indicated that germination increased to 79% at 4 days and increased slowly thereafter. Lysis of germ tubes was inhibited and most germ tubes were not lysed even after 48 days incubation. Small two- or three-celled macroconidia were commonly produced on germ tubes. In contrast, peak germination (39%) occurred at 2 days in rewetted soil incubated at 25 °C with germ tube lysis occurring rapidly between 4 and 8 days. Only sparse sporulation was observed. After 9 months, survival of F. roseum 'Sambucinum' was much greater in soil incubated at 6 °C than at 25 °C.Macroconidia required an exogenous source of carbon for high germination and formed one- or two-celled chlamydosporic macroconidia in media lacking exogenous carbon. After 9 months incubation under carbon starvation conditions at 25 °C chlamydosporic macroconidia had a longer latent period and a much slower rate of germination than macroconidia. Germinated macroconidia formed two- or three-celled macroconidia within 24 h when transferred to media lacking exogenous carbon. Four-celled macroconidia were produced by F. roseum 'Sambucinum' in a dilute glucose medium before exhaustion of the glucose while F. solani 'Coeruleum' formed chlamydospores in this medium after glucose depletion. Behavior of F. roseum 'Sambucinum' under carbon starvation conditions is similar to behavior in rewetted soil in the mode of sporulation and in the formation of chlamydosporic macroconidia, but differs by a lack of appreciable germination and by a greatly reduced lysis of fungal structures.

Leaf spot of bananas caused by Mycosphaerella musicola: action of oil on the life cycle of the pathogen

1968 ◽  
Vol 46 (12) ◽  
pp. 1495-1505 ◽  
Author(s):  
R. H. Stover ◽  
J. D. Dickson
Keyword(s):  
Incubation Period ◽  
Leaf Spot ◽  
Germ Tube ◽  
Tube Growth ◽  
Disease Development ◽  
Resistant Varieties ◽  
Mycosphaerella Musicola ◽  
Appressoria Formation ◽  
Ascospore Production ◽  
Germ Tube Growth

Oil spray reduced germination, germ tube growth, and appressoria formation by spores of Mycosphaerella musicola under field conditions for periods varying from 2 days to 2 weeks. Inhibition occurred only when spores were on the same leaf surface to which oil was applied. Appressoria formation and germ tube growth were reduced up to 33% and 25%, respectively. Conidia and ascospore production and dissemination were not adversely affected by oil spray. However, there were fewer sporodochia and perithecia in spots that were slow to develop as a result of oil spray. Oil application up to 2 weeks before or after infection increased the incubation period and the generation time, and reduced the number of spots. Oil is effective in retarding spot development when applied either before streaks appear or at the yellow streak stage of disease development. Oil, when applied during the incubation period or to yellow streaks, causes a variable amount of reduction in spotting and in only a minority of cases is disease development stopped completely. Therefore, leaf spot can build up on oil-sprayed plants when inoculum is abundant and weather favorable. The behavior of the pathogen on oil-sprayed susceptible banana plants is similar to that on partially resistant varieties.

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