Carbon and nitrogen requirements for macroconidial germination of Fusarium solani: dependence on conidial density

1970 ◽  
Vol 16 (8) ◽  
pp. 733-740 ◽  
Author(s):  
G. J. Griffin
Keyword(s):  
Fusarium Solani ◽  
Germ Tube ◽  
Tube Length ◽  
Inorganic Salts ◽  
Percentage Germination ◽  
Medium Ph ◽  
Carbon And Nitrogen ◽  
Germ Tube Length ◽  
Germ Tubes

Washed, PGA-grown macroconidia of F. solani did not require exogenous carbon or nitrogen for rapid (within 7 h), complete germination in a phosphate-buffered inorganic salts medium (pH 5.7) when the density of conidia was 3 × 103/ml or 3 × 102/ml. Rapid germination of macroconidia was fully dependent on exogenous carbon at 3 × 105 conidia/ml. Full dependence on both exogenous carbon and nitrogen was observed near 1 × 106 conidia/ml. Incomplete and slow germination of macroconidia was observed over 978 h at 6.4 × 105 and 3.2 × 105 conidia/ml in the absence of exogenous carbon and nitrogen.When glucose and NH4Cl were supplied at 4.0 μg C plus 0.26 μg N/ml or 40 μg C plus 2.6 μg N/ml, percentage germination of macroconidia, number of germ tubes/macroconidium, and mean germ tube length increased as the density of conidia decreased between 6.4 × 105 and 6.4 × 104 conidia/ml. Percentage germination increased as conidial density decreased between 3.1 × 106 and 3.1 × 104 conidia/ml when glucose and NH4Cl were supplied at each density at constant low amounts/conidium. Chlamydo–spore morphogenesis on germ tubes closely followed macroconidial germination in media initially containing low or no glucose and NH4Cl. The possible relation of these findings to macroconidial germination and chlamydospore morphogenesis in soil is discussed.

scholarly journals Effect of temperature, relative humidity and light on conidial germination of oak powdery mildew (Microsphaera alphitoides Griff. et Maubl.) under controlled conditions

2013 ◽  
Vol 65 (3) ◽  
pp. 1069-1077 ◽  
Author(s):  
P. Pap ◽  
B. Rankovic ◽  
S. Masirevic
Keyword(s):  
Relative Humidity ◽  
Powdery Mildew ◽  
Germ Tube ◽  
Inhibitory Effect ◽  
Conidial Germination ◽  
Effect Of Temperature ◽  
Tube Length ◽  
Controlled Conditions ◽  
Germ Tube Length ◽  
Germ Tubes

The influence of temperature, humidity and light on the conidial germination and germ tube elongation of oak powdery mildew (Microsphaera alphitoides Griff. et Maubl.) was studied in controlled conditions. The maximal germ tube length was attained at 25?C, whereas at lower and higher than optimal temperatures, germ tube growth was significantly lower. Germ tubes begin to develop at all values of relative humidity (10-100%), reaching the maximum length at 90%. The development of germ tubes was the most intense in full light and the lowest in total darkness. The artificial infection of floating leaves showed that an increasing age had an inhibitory effect on the mycelium development and spore formation. Since conidia play a crucial role in powdery mildew epidemiology, it is of particular importance to elucidate the influence of environmental factors in the complex relations that exist between the plant and its pathogen.

scholarly journals Influence of Iron on Cylindrocarpon Root Rot Development on Ginseng

2006 ◽  
Vol 96 (11) ◽  
pp. 1179-1187 ◽  
Author(s):  
Mahfuzur Rahman ◽  
Zamir K. Punja
Keyword(s):  
Enzyme Activity ◽  
Phenolic Compounds ◽  
Root Rot ◽  
High Performance ◽  
Germ Tube ◽  
Dry Weight ◽  
Colony Growth ◽  
Tube Length ◽  
Germ Tube Length

Cylindrocarpon root rot, caused by Cylindrocarpon destructans, is an important disease on ginseng (Panax quinquefolius) in Canada. We studied the effects of iron (Fe) on disease severity and pathogen growth. When Hoagland's solution was amended with Fe at 56 and 112 μg/ml compared with 0 μg/ml, disease initiation and final severity on hydroponically maintained ginseng roots was significantly (P<0.0001) enhanced. Under field conditions, wounding of roots with a fine needle followed by application of 0.05% FeNaEDTA to the rhizosphere of treated plants significantly enhanced Cylindrocarpon root rot in 2003 and 2004 compared with unwounded roots with Fe or wounded roots without Fe. Foliar applications of Fe (as FeNaEDTA) to ginseng plants three times during the 2002 and 2003 growing seasons significantly increased Fe levels in root tissues. These roots developed larger lesions following inoculation with C. destructans in vitro. When radioactive Fe (59Fe) was applied to the foliage of ginseng plants, it was detected in the secondary phloem and in cortical and epidermal tissues within 1 week. Artificially wounded areas on the roots accumulated more 59Fe than healthy areas. Diseased tissue also had threefold higher levels of phenolic compounds and Fe compared with adjoining healthy tissues. High-performance liquid chromatography analysis revealed enhanced levels of protocatechuic acid, chlorogenic acid, caffeic acid, ferulic acid, cinnamic acid, phloridizin, and quercetin. Phenolic compounds produced in diseased and wounded tissues sequestered Fe in vitro. The effects of Fe on mycelial growth, conidial germ tube length, and secondary branching of germ tubes of C. destructans were examined in vitro. When grown on Chrome-azurol S medium, Fe also was sequestered by C. destructans through siderophore production, which was visualized as a clearing pigmented zone at the margin of colonies. Mycelial dry weight was significantly increased in glucose/ yeast broth containing Fe at 56 or 112 μg/ml. Conidial germ tube length and secondary branching of hyphae also were enhanced after 8 and 16 h by Fe. Colony growth of C. destructans was not enhanced by Fe, but significantly greater spore production was observed with Fe at 56 and 112 μg/ml compared with no Fe in the medium. Although these levels of Fe had no effect on fungal pectinase enzyme activity, polyphenoloxidase (PPO) activity was significantly (P <0.0001) enhanced. We conclude that Fe enhances Cylindrocarpon root rot through enhanced pathogen growth, sporulation, and PPO enzyme activity. Fe sequestered by phenolic compounds produced in wounded tissues can enhance Fe levels at the site of infection. The pathogen also has the ability to sequester Fe at these sites.

Effect of the triazine herbicides Goltix and Igran on germination and growth of Aspergillus fumigatus, Fusarium oxysporum, Helminthosporium oryzae, and Verticillium agaricinum

1989 ◽  
Vol 67 (3) ◽  
pp. 737-741 ◽  
Author(s):  
E. E. A. Elwy ◽  
M. Osman ◽  
T. M. A. Abdel Rahman ◽  
I. M. K. Ismail
Keyword(s):  
Spore Germination ◽  
Radial Growth ◽  
Mycelial Growth ◽  
Germ Tube ◽  
Fungal Species ◽  
Tube Length ◽  
Liquid Cultures ◽  
Germ Tube Length ◽  
Helminthosporium Oryzae ◽  
Germination And Growth

The effect of two triazines on spore germination, radial growth, and biomass production were studied in A. fumigatus, F. oxysporum, H. oryzae, and V. agaricinum. Igran inhibited spore germination of all species to some extent and at 1000 ppm completely inhibited spore germination in A. fumigatus and F. oxysporum. Goltix inhibited germination of F. oxysporum and H. oryzae, but stimulated germination of A. fumigatus and V. agaricinum. Germ tube length was significantly decreased at high herbicide concentrations. Both derivatives reduced radial growth rate as well as mycelial growth in liquid cultures. The level of inhibition depends on the herbicide, its concentration, and the fungal species.

Modification of the exogenous carbon and nitrogen requirements for chlamydospore germination of Fusarium solani by contact with soil

1973 ◽  
Vol 19 (8) ◽  
pp. 999-1005 ◽  
Author(s):  
G. J. Griffin
Keyword(s):  
Fusarium Solani ◽  
Direct Contact ◽  
Axenic Culture ◽  
Fine Sand ◽  
Sand Soil ◽  
Carbon And Nitrogen ◽  
Axenic Conditions ◽  
Germ Tubes ◽  
Chlamydospore Germination ◽  
Exogenous Nitrogen

After exogenous carbon-independent macroconidium germination by Fusarium solani at 1 × 104 conidia/ml in axenic culture, chlamydospores were formed terminally on germ tubes. Low chlamydospore germination was supported under axenic conditions by 0.004 ng C/spore (calculated value), supplied as ethanol, or by 0.04 ng C/spore, supplied as glucose or several other sugars. Chlamydospores in direct contact with a nonsterile loamy fine sand soil (6.2 μg NH4+-N and 7.1 μg NO3−-N/g soil) had a greater exogenous carbon requirement and did not germinate until 2.0 ng glucose-C/spore was supplied. Supplemental exogenous nitrogen, added as NH4Cl, had little or no influence on percentage of germination at the levels of exogenous carbon supporting low germination, both in soil and in axenic culture. However, increasing the amounts of glucose plus NH4Cl supplied per spore increased percentage of chlamydospore germination more than increasing the amount of glucose alone for both soil and axenic systems. In axenic culture, complete germination was observed at 2.0 ng C plus 0.13 ng N/spore. Greater than 90% germination occurred for chlamydospores in contact with soil at the highest glucose plus NH4Cl level examined (200 ng C plus 13 ng N/spore), but not in glucose alone. Sterile acid-washed sand did not have a similar adverse effect on chlamydospore germination. Chlamydospores were nearly 100% germinable after 1 year of incubation in an inorganic salts medium under axenic conditions.

scholarly journals In vitro effect of substrate, temperature and photoperiod on Phakopsora pachyrhizi urediniospore germination and germ tube growth

2015 ◽  
Vol 41 (2) ◽  
pp. 101-106
Author(s):  
Marta Maria Casa Blum ◽  
Erlei Melo Reis ◽  
Francieli Tavares Vieira ◽  
Rita Carlini
Keyword(s):  
Substrate Temperature ◽  
Spore Germination ◽  
Leaf Extract ◽  
Germ Tube ◽  
Tube Growth ◽  
Tube Length ◽  
Germ Tube Length ◽  
Soybean Leaf ◽  
Germ Tube Growth

In vitro experiments were conducted to assess the effects of substrate, temperature and time of exposure to temperature and photoperiod on P. pachyrhizi uredospore germination and germ tube growth. The following substrates were tested: water-agar and soybean leaf extract-agar at different leaf concentrations (0.5, 1.0, 2.0 and 4.0 g of leaves and 15g agar/L water), temperatures (10, 15, 20, 25, 30, and 35oC) and times of exposure (1, 2, 3, 4, 5, 6, 7, and 8 hours) to temperature and 12 different photoperiods. The highest germination and germ tube length was found for the soybean leaf extract agar. Maximum P. pachyrhizi uredospore germination was obtained at 21.8 and 22.3°C, and maximum germ tube growth at 21.4 and 22.1°C. The maximum uredospore germination was found at 6.4 hours exposure, while the maximum germ tube length was obtained at 7.7 h exposure. Regarding photoperiod, the maximum spore germination and the maximum uredospore germ tube length were found in the dark. Neither spore germination nor uredospore germ tube growth was completely inhibited by the exposure to continuous light.

scholarly journals The Longevity of Conidia of Sclerotinia Fructicola (Wint.) Rehm Under Field Conditions

1968 ◽  
Vol 21 (5) ◽  
pp. 937 ◽  
Author(s):  
P T Jenkins
Keyword(s):  
Germ Tube ◽  
Tree Canopy ◽  
Field Conditions ◽  
Tube Length ◽  
Sterile Water ◽  
Mature Fruit ◽  
Germ Tube Length ◽  
Unsterilized Soil

The longevity of conidia of S. fructicola was determined in an orchard environment. Less than 1 % of conidia remained viable after exposure or 8 days in the tree canopy. In addition to reducing viability, exposure reduced both germ tube length and infection of mature fruit. Conidia prepared in a suspension in sterile water, to simulate those that are dispersed in rain, lost viability more rapidly on exposure than conidia that remained dry. When conidia were in contact with unsterilized soil for 24 hr they also lost viability.

scholarly journals APPRESSORIUM FORMATION IN THE PECAN SCAB FUNGUS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 627f-627
Author(s):  
K.M.T. Cason ◽  
I.E. Yates
Keyword(s):  
Germ Tube ◽  
Light And Electron Microscopy ◽  
Preliminary Evidence ◽  
Tube Length ◽  
Dialysis Membrane ◽  
Appressorium Formation ◽  
Pecan Scab ◽  
Germ Tubes

Pecan scab, caused by the fungus Cladosporium caryigenum (Ell. et Lant) Gottwald, produces more damage to pecan than all other diseases and insects combined. Early events during infection are critical to disease establishment and to expression of host resistance, but have not been examined previously. Objectives of this research were to determine if there is regulation of appressorial formation and if it is related to resistance. Pre-infectional host-pathogen interactions were studied in vivo (on leaves) and in vitro (on callus, dialysis membrane, and agar) with light and electron microscopy. Leaves, callus tissue, dialysis membranes, and agar were inoculated with scab conidia and were incubated under conditions optimum for germination. Conidia germinate and produce a germ tube on agar and dialysis membrane, but appressoria are not formed. Appressoria form on pecan callus, but germ tubes are long. Long germ tubes are often associated with resistant disease reactions. In vivo, appressoria form readily, but germ tube length varies depending on the location of the spore on the leaf surface. Preliminary evidence indicates that surface topography affects induction of appressorium formation in the scab fungus.

Competition for endogenous and exogenous nutrients between Sporobolomyces roseus and Cochliobolus sativus

1984 ◽  
Vol 62 (11) ◽  
pp. 2463-2468 ◽  
Author(s):  
N. J. Fokkema
Keyword(s):  
Germ Tube ◽  
Conidial Germination ◽  
Glass Slide ◽  
Cochliobolus Sativus ◽  
Tube Length ◽  
Glass Slides ◽  
Germ Tube Length ◽  
Cellophane Sheet ◽  
Sporobolomyces Roseus ◽  
Exogenous Nutrients

Sporobolomyces roseus reduced conidial germination of Cochliobolus sativus on glass slides covered with a thin layer (0.1 mm) of water agar or Czapek Dox agar by ca. 60 and 99%, respectively. On wheat flag leaves S. roseus reduced conidial germination by ca. 15% but reduced germ tube length by ca. 48%. However, cell-free aqueous diffusates collected from water agar slides and leaves with and without S. roseus showed no differential effect on Co. sativus when bioassayed on water agar slides. Diffusates from Czapek Dox agar with S. roseus reduced conidial germination by 46% when compared with the nutrient-rich diffusate from Czapek Dox agar alone. Although this demonstrated the ability of the yeasts to reduce the amount of exogenous nutrients, this did not account for the 99% reduction found in the presence of S. roseus. When Co. sativus was separated from S. roseus on Czapek Dox agar by two layers of cellophane, the reduction was the same and maintained for at least 3 days. If Co. sativus was removed from S. roseus by transferring the upper cellophane sheet to a glass slide, germination was restored, indicating that the yeasts formed also a continuous drain of endogenous nutrients from the conidia. A steady supply of amino acids and (or) glucose to Czapek Dox agar slides with S. roseus and Co. sativus could only partially overcome the antagonistic interaction.

The effects of elevated temperatures on spore swelling and germination in Aspergillus niger

1972 ◽  
Vol 18 (3) ◽  
pp. 289-297 ◽  
Author(s):  
J. G. Anderson ◽  
J. E. Smith
Keyword(s):  
Aspergillus Niger ◽  
Germ Tube ◽  
Elevated Temperatures ◽  
Nitrogen Sources ◽  
Tube Formation ◽  
Carbon And Nitrogen ◽  
Gaseous Environment ◽  
Spherical Cells ◽  
Spherical Growth ◽  
Germ Tubes

Exogenous carbon and nitrogen sources were necessary for complete swelling (spherical growth) and germ-tube formation from Aspergillus niger spores. The rate of spherical growth was low at 30°, maximum at 38°, and decreased at higher temperatures until at 47° inhibition was complete. At temperatures from 35° to 44° the final spore size was similar and greater than at 30° although the time taken to reach this size varied. Germ-tube formation occurred in from 97 to 99% of the spores with a good degree of synchrony between 30° and 38°. At temperatures from 38° to 43° the proportion of spores which produced germ tubes gradually decreased with a concurrent loss of synchrony. At 44° germ-tube formation was completely inhibited although spherical growth could occur over a prolonged period to produce large spherical cells. This increase of cell volume was apparently accompanied by a system of wall extension which involved wall synthesis. Under conditions of spore crowding an inhibition became apparent which affected only the initiation of spherical growth and not the spherical-growth process itself. Other effects of spore crowding were observed and were attributed to alterations in the gaseous environment. Increased spherical growth was always accompanied by a greater degree of branching of the germ tube when produced and a hypothesis relating these effects is suggested.

Aktive Aufnahme von Zuckern durch Zellen von Neurospora crassa unter Beteiligung eines enzymatischen Systems mit Permease-Eigenschaften II

1967 ◽  
Vol 22 (2) ◽  
pp. 188-195 ◽  
Author(s):  
Walter Klingmüller
Keyword(s):  
Neurospora Crassa ◽  
Germ Tube ◽  
Dry Weight ◽  
Tube Length ◽  
Enzymatic System ◽  
Aqueous Extracts ◽  
Millipore Filter ◽  
Base Level ◽  
Germ Tube Length ◽  
Insoluble Form

Sorbose-transport in Neurospora has been investigated further. Methods and results were as follows:Conidia pregerminated with fructose were incubated with increasing amounts of 14C-labelled sorbose, their radioactivity was measured by millipore-filter technique. Sorbose uptake followed Michaelis-Menten kinetics, with Km = 5.1 ± 1.2 mM and Vmax=0.16 ± 0.05 mg sorbose/mg dry weight/minute. It was inhibited slightly by addition of fructose, and strongly by addition of glucose; the exact type of inhibition was concentration dependent.Ungerminated conidia or pregerminated conidia were incubated with 14C-labelled sorbose. A base level of sorbose uptake by ungerminated conidia, and an increasing uptake with increasing pregermination time of the conidia was found; the uptake was proportional to germ-tube length.Supernatants of ungerminated or germinated conidia were checked for sugars related to sorbose by enzymatic and bio-assays. The results were negative.Radiopaperchromatography of aqueous extracts of incubated conidia revealed that sorbose as opposed to fructose is not phosphorylated during uptake, but accumulated as the pure sugar inside the cells. Ca. 90% of the fructose but barely 7% of sorbose taken up is transformed into a water insoluble form after 60 minutes incubation of the conidia.Conidia incubated with labelled sorbose were treated with unlabelled sorbose or Na-azide. The accumulated labelled sorbose was driven out by both treatments (with sorbose ca. 65% with Naazide ca. 80% after 60 minutes).The data support the hypothesis proposed earlier1 that sorbose is taken up into conidia of Neurospora crassa by means of active transport, mediated by an inducible enzymatic system of the permease-type.

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