Interaction of Xanthomonas campestris pv. undulosa or Pseudomonas cepacia with Septoria nodorum in vitro and in vivo

1982 ◽  
Vol 28 (2) ◽  
pp. 205-210 ◽  
Author(s):  
J. B. Jones ◽  
C. W. Roane
Keyword(s):  
Spore Germination ◽  
Xanthomonas Campestris ◽  
Leaf Extract ◽  
Germ Tube ◽  
Tube Length ◽  
Pseudomonas Cepacia ◽  
Septoria Nodorum ◽  
Germ Tube Length ◽  
Wheat Leaf

Xanthomonas campestris pv. undulosa did not inhibit growth or spore germination of Septoria nodorum on wheat leaf extract agar, whereas Pseudomonas cepacia produced a zone of complete inhibition of spore germination up to 17.5 mm and reduced germination up to 5 cm from the bacterial front. Culture filtrates of the two bacteria grown in 'Blueboy' or 'Arthur' wheat leaf extract broth were incorporated into fresh wheat leaf extract broth. These filtrates caused a reduction in growth (dry weight) of S. nodorum compared with growth in unamended extract. Fungal mass was considerably lower in P. cepacia filtrate of 'Arthur' wheat than in the X. campestris pv. undulosa filtrate or the control. The extent of reduction by P. cepacia filtrate suggests an antibiotic effect. In phosphate buffer, X. campestris pv. undulosa reduced spore germination and germ tube length of S. nodorum, while P. cepacia inhibited germination and germ tube growth completely. In vivo, X. campestris pv. undulosa had no effect on spore germination but did reduce germ tube length whereas P. cepacia inhibited both parameters.

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.

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.

scholarly journals Biological Control of Celery Powdery Mildew Disease Caused by Erysiphe heraclei DC In Vitro and In Vivo Conditions

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2342
Author(s):  
Hamada F. A. Ahmed ◽  
Mahmoud F. Seleiman ◽  
Adel M. Al-Saif ◽  
Maha A. Alshiekheid ◽  
Martin L. Battaglia ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Disease Severity ◽  
Germ Tube ◽  
The Other ◽  
Biocontrol Agents ◽  
Tube Length ◽  
Conidia Germination ◽  
Germ Tube Length

The present study aimed to investigate the potentiality of certain biocontrol agents, namely Bacillus subtilis, B. pumilus, B. megaterium, Pseudomonas fluorescens, Serratia marcescens, Trichoderma album, T. harzianum and T. viride, as well as the synthetic fungicide difenoconazole to control celery powdery mildew caused by Erysiphe heraclei DC, in vitro (against conidia germination and germ tube length of E. heraclei) and in vivo (against disease severity and AUDPC). In vitro, it was found that the antifungal activity of the tested biocontrol agents significantly reduced the germination percentage of the conidia and germ tube length of the pathogen. The reduction in conidia germination ranged between 88.2% and 59.6% as a result of the treatment with B. subtilis and T. album, respectively compared with 97.1% by the synthetic fungicide difenoconazole. Moreover, the fungicide achieved the highest reduction in germ tube length (92.5%) followed by B. megaterium (82.0%), while T. album was the least effective (62.8%). Spraying celery plants with the tested biocontrol agents in the greenhouse significantly reduced powdery mildew severity, as well as the area under the disease progress curve (AUDPC), after 7, 14, 21 and 28 days of application. In this regard, B. subtilis was the most efficient followed by B. pumilus, S. marcescens and B. megaterium, with 80.1, 74.4, 73.2 and 70.5% reductions in disease severity, respectively. In AUDPC, reductions of those microorganisms were 285.3, 380.9, 396.7 and 431.8, respectively, compared to 1539.1 in the control treatment. On the other hand, the fungicide difenoconazole achieved maximum efficacy in reducing disease severity (84.7%) and lowest AUDPC (219.3) compared to the other treatments. In the field, all the applied biocontrol agents showed high efficiency in suppressing powdery mildew on celery plants, with a significant improvement in growth and yield characteristics. In addition, they caused an increase in the concentration of leaf pigments, and the activities of defense-related enzymes such as peroxidase (PO) and polyphenol oxidase (PPO) and total phenol content (TPC). In conclusion, the results showed the possibility of using tested biocontrol agents as eco-friendly alternatives to protect celery plants against powdery mildew.

scholarly journals Effect of Legume Extracts on Germination, Seedling Health of Beans (Phaseolus vulgaris L.) and Soil Microorganisms

2019 ◽  
pp. 1-13
Author(s):  
Oliver Otieno Okumu ◽  
James Wanjohi Muthomi ◽  
John Ojiem ◽  
Rama Narla ◽  
John Huria Nderitu
Keyword(s):  
Seed Germination ◽  
Spore Germination ◽  
Mycelial Growth ◽  
Germ Tube ◽  
Tube Length ◽  
Green Manures ◽  
Seedling Length ◽  
Germ Tube Length ◽  
Ethanol Extracts ◽  
Germ Tube Elongation

Application of undecomposed green manure has been reported to cause poor emergence and establishment of common beans in the field. Therefore, to understand the mechanisms’ contributing to the poor crop establishment, the effect of extracts from fresh and decomposed legume green manures on bean seed germination, fungal mycelial growth, spore germination and germ tube elongation were evaluated. The extracts were prepared in either ethanol or distilled water. Data was collected on percentage seed germination, seedling length, mycelial radial growth, spore germination and germ tube elongation. Ethanol extracts from fresh lablab inhibited bean germination by 56%, increased mean germination time to 8 days, and decreased germination index while ethanol extracts of groundnut and beans caused highest inhibition in bean shoot length and reduced biomass. Ethanol extracts from fresh green manures significantly inhibited fungal mycelial growth while the aqueous extracts from beans, groundnuts and soybean had significant level of antifungal activity while aqueous lablab extracts stimulated mycelial. Aqueous extract of lablab and soybean enhanced spore germination by over 70% with more pronounced effect on germ tube length and number of germ tubes by 8.0% and 13% respectively. The study comparatively reveals that the extract of lablab was inhibitory to common bean germination compared to other legume extracts and also stimulated the growth of root rot pathogens that may have resulted in poor establishment of beans.

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.

Antagonistic interactions of phylloplane bacteria with Drechslera dictyoides (Drechsler) Shoemaker

1977 ◽  
Vol 23 (6) ◽  
pp. 710-715 ◽  
Author(s):  
Brian Austin ◽  
Colin H. Dickinson ◽  
Michael Goodfellow
Keyword(s):  
Lolium Perenne ◽  
Xanthomonas Campestris ◽  
Germ Tube ◽  
Disease Symptoms ◽  
In Vivo Experiments ◽  
Drechslera Dictyoides ◽  
Antagonistic Interactions ◽  
Germ Tube Elongation

Strains of Listeria denitrificans (E2), Psendomonas fluorescens (C37 and C92), and Xanthomonas campestris (D119), isolated from the phylloplane of Lolium perenne (S24), were antagonistic to Drechslera dictyoides (Drechsler) Shoemaker. From in vitro and in vivo experiments it was deduced that their mode of activity included an initial inhibition of spore germination, a retardation in the rate of germ-tube elongation, and ultimately lysis of the hyphae. The effects were expressed on the plant in terms of reduced levels of disease symptoms and sporulation.

Soil fungistasis: fungus spore germination in soil at spore densities corresponding to natural population levels

1974 ◽  
Vol 20 (5) ◽  
pp. 751-754 ◽  
Author(s):  
Gary J. Griffin ◽  
Robert H. Ford
Keyword(s):  
Natural Population ◽  
Spore Germination ◽  
Tube Length ◽  
Test Fungus ◽  
Germ Tube Length ◽  
Fungus Spore ◽  
Soil Fungistasis ◽  
Time Observation ◽  
First Time ◽  
Spore Densities

An autoradiographic spore-location technique is described that allows for the first time observation of spore germination in soil at low natural population levels (103 to 104 spores/g soil). When Fusarium solani f. sp. phaseoli was used as a test fungus, percentage macroconidial germination was greatest in nonsterile soil at 3 × 103 and 3 × 104 conidia/g soil, and percentage germination decreased sharply with increasing conidial density. Mean germ tube length was greater at 3 × 103 than at 3 × 104 conidia/g soil. The results indicate that inhibition of spore germination (apparent soil fungistasis) of a fungus in soil environments at conventionally used high spore densities (105 to 106 spores/g soil) may not mean that spores of the fungus will be equally inhibited in the same environments at lower natural population levels.

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.

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