scholarly journals Germination of Peronospora Tabaoina: Effect of Temperature

1961 ◽  
Vol 14 (1) ◽  
pp. 58 ◽  
Author(s):  
IAM Cruickshank
Keyword(s):  
Germ Tube ◽  
Effect Of Temperature ◽  
Tube Length ◽  
Peronospora Tabacina ◽  
In Vitro Technique ◽  
Germ Tube Length

In an investigation into the effect of temperature on the germination and germ-tube length of Peronospora tabacina Adam using an in vitro technique the following results were obtained:

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.

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.

The effect of light and temperature on in vitro germination and germ tube growth of urediniospores of Tranzschelia discolor

1992 ◽  
Vol 43 (3) ◽  
pp. 451 ◽  
Author(s):  
PJ Ellison ◽  
BR Cullis ◽  
PF Kable
Keyword(s):  
Light Intensity ◽  
Germ Tube ◽  
Tube Growth ◽  
Tube Length ◽  
In Vitro Germination ◽  
Germ Tube Length ◽  
Tranzschelia Discolor ◽  
Effect Of Light ◽  
Germ Tube Growth

The effect of light on in vitro germination of urediniospores of Tranzschelia discolor was studied over time at different intensitities (up to 400 8E m-2 s-l) within the temperature range 5�C to 20�C. A model was also developed from the data to predict germination at different combinations of light, temperature and times of leaf wetness. Light retarded the germination process, and its effect increased in direct proportion to intensity. At 20�C, for example, the time taken to exceed 80% germination increased from 2 h in the dark to 9 h at 200 8E m-2 s-l. The model showed that there was an interaction between light and temperature, with the effect of light becoming more pronounced as the temperature declined below 20�C. Germination percentages of the order of 90% were, however, recorded within 24 h at all combinations of light intensity and temperature studied. Light also influenced germ tube growth, causing a reduction in the rate of growth. As in germination, its effect increased with increasing light intensity. At 20�C, the average germ tube length at 9 h was 541 8m in the dark, compared with 227 8m at 200 8E m-2 s-1 and 148 8m at 400 8E m-2 s-l. A similar effect was observed at 5�C, where the average germ tube length at 24 h was 274 8m in the dark compared with 157 8m at 200 8E m-2 s-l. The effects of light on the germination and germ tube growth of urediniospores under field conditions are discussed.

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 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.

The effect of temperature on in vitro germination and germ tube growth of urediniospores of Tranzschelia discolor

1990 ◽  
Vol 41 (3) ◽  
pp. 479 ◽  
Author(s):  
PJ Ellison ◽  
BR Cullis ◽  
RW Bambach ◽  
PF Kable
Keyword(s):  
Germ Tube ◽  
Three Dimensional ◽  
Tube Growth ◽  
Effect Of Temperature ◽  
In Vitro Germination ◽  
Three Dimensional Models ◽  
C 30 ◽  
Tranzschelia Discolor ◽  
Germ Tube Growth

The effect of temperature on in vitro germination and germ tube growth of urediniospores of Tranzschelia discolor was studied over time under constant temperature conditions. Studies were carried out on 1% water agar in the dark at 3�C, 5�C, 8�C, 10�C, 15�C, 20�C, 25�C, 28�C, 30�C and 32�C. Germination was observed at all temperatures between 5 and 30'C, and occurred rapidly over most of this range. At 2 h, germination exceeded 80% at temperatures between 10 and 28�C, and this level was reached at 3 h at 8�C. Germination at 5 and 30�C was much reduced and at 7 h reached only 44% and 38% respectively. Germ tube growth occurred most vigorously at 15 and 20�C, reaching lengths in excess of 500 8m at 9 h. The optimum range was narrower than that for germination, and growth was reduced or poor at 8�C, 10�C, 25�C and 28�C, which were favourable temperatures for germination. Average germ tube lengths at 9 h at these temperatures were 55, 245, 273 and 62 8m, respectively. Three-dimensional models were derived relating germination and germ tube growth to time and temperature.

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 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 Effects of Sporidiobolus pararoseus Y16 on Postharvest Blue Mold Decay and the Defense Response of Apples

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Lina Zhao ◽  
Yiwen Sun ◽  
Dongbiao Yang ◽  
Jun Li ◽  
Xiangyu Gu ◽  
...  
Keyword(s):  
Defense Response ◽  
Apple Fruit ◽  
Penicillium Expansum ◽  
Tube Length ◽  
Blue Mold ◽  
Expression Levels ◽  
Germ Tube Length ◽  
Fruit Decay ◽  
Sporidiobolus Pararoseus

The efficacy of Sporidiobolus pararoseus Y16 in controlling postharvest blue mold caused by Penicillium expansum on apples and the defense response involved were evaluated. The results suggested that the decay incidence of blue mold of apples treated by S. pararoseus Y16 was significantly reduced compared with the control. In vitro testing indicated that germination of spores and germ tube length of P. expansum were markedly inhibited by S. pararoseus Y16. Meanwhile, polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia lyase (PAL), and catalase (CAT) activities and several pathogenesis-related (PR) gene expression levels (including PR3, PR4, PR5, and PR9) were determined. In apples, the activities of PPO, POD, CAT, and PAL were significantly induced by S. pararoseus Y16 treatment compared with the control fruits. The relative expression levels of PR3 and PR4 were significantly induced at 4 and 6 d, while PR5 was significantly induced at 4 and 6 d and PR9 was significantly induced at 4 d. Therefore, the reduction in apple fruit decay by S. pararoseus Y16 treatment could be related to the increased activities of related enzymes and proteins involved in the defense against pathogens, which suggest that S. pararoseus Y16 is a potential antagonistic yeast.

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.

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