Rhizosphere Microorganisms From the Jarrah Forest of Western Australia and Their Effects on Vegetative Growth and Sporulation in Phytophthora cinnamomi Rands

1987 ◽  
Vol 35 (5) ◽  
pp. 567 ◽  
Author(s):  
DIL Murray
Keyword(s):  
Vegetative Growth ◽  
Mycelial Growth ◽  
Phytophthora Cinnamomi ◽  
Inhibitory Effect ◽  
The Other ◽  
Microbial Competition ◽  
Eucalyptus Marginata ◽  
Rhizosphere Microflora ◽  
Dual Cultures ◽  
Zoospore Discharge

Soil dilution plate techniques were used to compare the numbers of bacteria, actinomycetes and fungi in the rhizospheres of Acacia pulchella, Banksia grandis and Eucalyptus marginata (jarrah). The most frequently isolated microorganisms and those detected in significantly different numbers in the rhizospheres of the three species were tested for their effects on sporangium production, zoospore discharge, zoospore germination and mycelial growth of the jarrah dieback pathogen Phytophthora cinnamomi. The total population of fungi in rhizosphere soil from B. grandis was much greater than that found in the rhizospheres of the other two species while the convesse was true for bacteria and actinomycetes, of which the largest populations were associated with A. pulchella. Penicillium spinulosum outnum- bered the combined population of other fungi in the Banksia rhizosphere but formed a much smaller proportion of the jarrah and Acacia rhizosphere microfloras, particularly the latter. P. spinulosum had no effect on mycelial growth or zoospore discharge in P. cinnamomi; it had some ability to stimulete sporangium production and, although it partly suppressed spore germination, the inhibitory effect was less pronounced than that noted for most other microorganisms. In contrast, microorganisms which strongly inhibited mycelial growth, zoospore discharge and germination represented a greater proportion of the Acacia rhizosphere microflora compared with the other microfloras, especially that of B. grandis. While some actinornycetes and fungi produced antibiotics that inhibited vegetative growth of P. cinnamomi in dual cultures, mycelial inhibition was often attributable to nutrient depletion of agar media by the test microorganisms. Similarly, nutrient deprivation resulting from microbial competition for substrates was also considered to be the stimulus for sporangium production in liquid media. The results are discussed in relation to previously reported suppression of P. cinnamomi in forest soils beneath stands of A. pulchella and the associated implications of this for biological control of jarrah dieback.

Infection by Phytophthora cinnamomi Rands of Roots of Eucalyptus calophylla R.Br. and Eucalyptus marginata Donn. ex Sm

1977 ◽  
Vol 25 (5) ◽  
pp. 483 ◽  
Author(s):  
N Malajczuk ◽  
AJ Mccomb ◽  
CA Parker
Keyword(s):  
Phytophthora Cinnamomi ◽  
Light And Electron Microscopy ◽  
Inhibitory Effect ◽  
Lateritic Soil ◽  
Root Damage ◽  
Mature Trees ◽  
Cortical Cells ◽  
Eucalyptus Marginata ◽  
Seedling Roots ◽  
Loam Soil

On lateritic podzolic soils in Western Australia Eucalyptus calophylla is resistant to Phytophthora cinnamomi whereas Eucalyptus marginata is susceptible and eventually killed by the pathogen. On loam soils both eucalypts are resistant. Possible mechanisms for resistance of E. calophylla in lateritic soil and the inhibitory action of loam soils were investigated. Aseptically raised eucalypt seedlings succumbed to infection in liquid culture tubes. The mechanism of infection was compared by light and electron microscopy which showed similar fungal invasion and penetration into roots of both eucalypt species. Vegetative hyphae initially penetrated intercellularly and proliferated rapidly within cortical and stelar tissue. Intracellular invasion of these tissues occurred 48hr after initial infection through dissolution of the host cell wall. Chlamydospores were formed within a number of cortical cells. Unsuberized roots of mature trees produced aseptically showed reactions to invasion similar to those of the eucalypt seedling roots. Suberized roots were not invaded. The addition of small quantities of lateritic soil to sterile sand so as to introduce soil micro-organisms without altering the chemical and physical status of the sand, and subsequent inoculation of the sand with P.cinnamomi, resulted in a reduction of root damage on both eucalypts when compared with seedlings raised in sterile sand. Roots of E.calophylla were less severely damaged than those of E.marginata. The addition of small quantities of loam soil significantly reduced root damage in seedlings of both species. These results parallel both pot experiments and field observations, and suggest that microorganisms of the rhizosphere may be an important factor in the resistance of E.calophylla to infection, and in the inhibitory effect of loam soil on P.cinnamomi.

scholarly journals Diffusible Compounds Produced by Hanseniaspora osmophila and Gluconobacter cerinus Help to Control the Causal Agents of Gray Rot and Summer Bunch Rot of Table Grapes

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 664
Author(s):  
Matías Olivera ◽  
Ninoska Delgado ◽  
Fabiola Cádiz ◽  
Natalia Riquelme ◽  
Iván Montenegro ◽  
...  
Keyword(s):  
Mycelial Growth ◽  
Inhibitory Effect ◽  
Biocontrol Agents ◽  
Environmental Cost ◽  
Antifungal Compounds ◽  
Table Grapes ◽  
Dual Cultures ◽  
Bunch Rot ◽  
Direct Bioautography

Gray and summer bunch rot are important diseases of table grapes due to the high economic and environmental cost of their control with synthetic fungicides. The ability to produce antifungal compounds against the causal agents Botrytis, Aspergillus, Penicillium, and Rhizopus of two microorganisms isolated from table grapes and identified as Hanseniaspora osmophila and Gluconobacter cerinus was evaluated. In dual cultures, both biocontrol agents (together and separately) inhibited in vitro mycelial growth of these pathogens. To identify the compounds responsible for the inhibitory effect, extractions were carried out with organic solvents from biocontrol agents separately. Through dual cultures with pathogens and pure extracts, only the hexane extract from H. osmophila showed an inhibitory effect against Botrytis cinerea. To further identify these compounds, the direct bioautography technique was used. This technique made it possible to determine the band displaying antifungal activity at Rf = 0.05–0.2. The compounds present in this band were identified by GC-MS and compared to the NIST library. The most abundant compounds, not previously reported, corresponded to alkanes, ketones, alcohols, and terpenoids. H. osmophila and G. cerinus have the potential to control the causal agents of gray and summer bunch rot of table grapes.

scholarly journals Inhibitory effect of the glucosinolate–myrosinase system on Phytophthora cinnamomi and Pythium spiculum

2019 ◽  
Vol 55 (No. 2) ◽  
pp. 93-101 ◽  
Author(s):  
Francisco Teodoro Arroyo Cordero ◽  
Rocío Rodríguez-Arcos ◽  
Ana Jiménez-Araujo ◽  
Rafael Guillén-Bejarano ◽  
María José Basallote ◽  
...  
Keyword(s):  
Mycelial Growth ◽  
High Performance ◽  
Phytophthora Cinnamomi ◽  
Inhibitory Effect ◽  
Reversed Phase ◽  
Field Application ◽  
Additional Information ◽  
Array Detection ◽  
Important Additional Information

Glucosinolate extracts from sprouts of common Brassica nigra, B. juncea cv. Scala, B. carinata cv. Eleven, and Sinapis alba cv. Ludique were analysed by reversed phase high-performance liquid chromatography-diode array detection-mass spectrometry. The effect of the glucosinolate–myrosinase system on in vitro mycelial growth of Phytophthora cinnamomi Rands and Pythium spiculum B. Paul was assessed. Likewise, sinigrin and sinalbin monohydrate commercial standards were also tested. The extracts from B. carinata, which contained 159 mmol/g plant DW equivalent (85% sinigrin, 5% gluconapin, and 3% glucotropaeolin), were the most effective against Phytophthora and Pythium isolates used in this study. However, the extract from S. alba, which contained 1 180 mmol/g (100% sinalbin), did not inhibit the mycelial growth of the isolates tested. The use of the glucosinolate-myrosinase system provides important additional information to advance in the implementation of field application of brassicaceous amendments for the control of soil-borne pathogens.

Indirect Effect of Floristic Composition on Production of Sporangia by Phytophthora cinnamomi in Jarrah Forest Soils

1985 ◽  
Vol 33 (1) ◽  
pp. 109 ◽  
Author(s):  
DIL Murray ◽  
DD Darling ◽  
LR Mcgann
Keyword(s):  
Direct Effect ◽  
Forest Soils ◽  
Indirect Effect ◽  
Physical Environment ◽  
Phytophthora Cinnamomi ◽  
Floristic Composition ◽  
Jarrah Forest ◽  
Eucalyptus Marginata ◽  
Per Se ◽  
Zoospore Discharge

Production of sporangia and zoospore discharge by Phytophthora cinnamomi were investigated in jarrah forest soils collected beneath Acacia pulchella, Banksia grandis and Eucalyptus marginata and incubated under conditions which excluded a direct effect of these species on the soil physical environment. Sporangium production was always significantly greater in soils from B. grandis than in soils from A. pulchella; soils from E. marginata gave intermediate results. There was also evidence that discharge of zoospores was suppressed in soils from A. pulchella. Although three isolates of P. cinnamomi differed in their abilities to sporulate per se, they responded similarly to different treatments.

Inhibition of Germination, Outgrowth, and Vegetative Growth of Clostridium botulinum 67B by Spice Oils

1990 ◽  
Vol 53 (9) ◽  
pp. 755-758 ◽  
Author(s):  
ADNAN A. ISMAIEL ◽  
M. D. PIERSON
Keyword(s):  
Spore Germination ◽  
Vegetative Growth ◽  
Clostridium Botulinum ◽  
Inhibitory Effect ◽  
Black Pepper ◽  
The Other

The oils of clove, thyme, black pepper, pimenta, origanum, garlic, onion, and cinnamon were tested for their activity on germination, outgrowth, and vegetative growth of Clostridium botulinum 67B in broth media. Garlic, onion, cinnamon, thyme, origanum, and black pepper oils at a concentration of 100 ppm prevented germination of C. botulinum 67B spores. Clove and pimenta oils at a concentration of 150 ppm prevented germination. The effect of spice oils on spore germination was reversible. The oils of black pepper and clove had a greater inhibitory effect on vegetative growth than the other oils. None of the oils had a significant effect on outgrowth.

The Microflora of Unsuberized Roots of Eucalyptus calophylla R.Br. And Eucalyptus marginata Donn ex Sm. Seedlings Grown in Soil Suppressive and Conducive to Phytophthora cinnamomi Rands. I. Rhizosphere Bacteria, Actinomycetes and Fungi

1979 ◽  
Vol 27 (3) ◽  
pp. 235 ◽  
Author(s):  
N Malajczuk ◽  
AJ Mccomb
Keyword(s):  
Unit Area ◽  
Phytophthora Cinnamomi ◽  
Natural Infection ◽  
Differential Susceptibility ◽  
Root Surface ◽  
Lateritic Soil ◽  
Eucalyptus Marginata ◽  
Rhizosphere Microflora ◽  
Rhizosphere Population ◽  
Loam Soil

An investigation was made of the microflora associated with unsuberized roots of Eucalyptus marginata and Eucalyptus calophylla raised in different soils. The studies were made for 'conducive' lateritic soil (in which E. marginata is susceptible to infection by Phytophthora cinnamomi but E. Calophylla is resistant); and in 'suppressive' loam soil in which both eucalypt species are unaffected by the pathogen. Lateritic soil in some cases contained natural infection of P. cinnamomi. Rhizospheres of both species contained larger microflora populations (expressed as numbers per g of root) than in the soils. In general, the population of rhizosphere microflora was greater for E. Marginata than E. calophylla seedlings in the uninfected lateritic soil. Qualitative differences were also recorded in populations of bacteria, actinomycetes and fungi, and in particular, fluorescent pseudomonads were more numerous in the rhizosphere of E. marginata seedlings. Eucalypt seedlings raised in loam soil harboured greater microbial populations than in lateritic soil. This could in part be attributed to the higher nutrient and organic matter status of the loam. E. marginata had a greater total rhizosphere population, but actinomycetes were more numerous in the rhizosphere of E. calophylla. Qualitative differences in populations of bacteria, actinomycetes and fungi were also noted. In naturally infected lateritic soil the microflora populations were invariably lower than for the other soils. When the counts of bacteria and actinomycetes were expressed as numbers per mm2 of root surface, E. calophylla had a significantly higher number of propagules per unit area than E. marginata. The loam soil was an exception; there E. marginata had three times as many bacteria per unit area of the root surface as E. calophylla. It is suggested that the microflora population differences recorded for the two eucalypts in lateritic soil may contribute to the differential susceptibility of species to infection by P. cinnamomi; and that the higher populations of microflora in the loam soil contribute to the suppression of P. Cinnamomi in that soil.

Annual Increment of Eucalyptus marginata Trees on Sites Infested With Phytophthora cinnamomi

1988 ◽  
Vol 36 (1) ◽  
pp. 101 ◽  
Author(s):  
EM Davison ◽  
FCS Tay
Keyword(s):  
Growth Rates ◽  
Phytophthora Cinnamomi ◽  
The Other ◽  
Annual Increment ◽  
Eucalyptus Marginata ◽  
Infested Area

The annual increment of Eucalyptus marginata in forest infested with Phytophthora cinnamomi was compared with the growth of matched trees in adjacent uninfested forest, on two sites, for at least 4 years. On one site, trees in the infested area grew significantly faster than trees in the uninfested forest. On the other site growth rates were similar.

scholarly journals Effect of Potassium Channel Modulators on Morphine Withdrawal in Mice

2010 ◽  
Vol 4 ◽  
pp. SART.S6211 ◽  
Author(s):  
Vikas Seth ◽  
Mushtaq Ahmad ◽  
Prerna Upadhyaya ◽  
Monika Sharma ◽  
Vijay Moghe
Keyword(s):  
Potassium Channel ◽  
Withdrawal Syndrome ◽  
Channel Blocker ◽  
Inhibitory Effect ◽  
Morphine Withdrawal ◽  
The Other ◽  
Opioid Antagonist ◽  
Potassium Channel Openers ◽  
Potassium Channel Modulators ◽  
Withdrawal Signs

The present study was conducted to investigate the effect of potassium channel openers and blockers on morphine withdrawal syndrome. Mice were rendered dependent on morphine by subcutaneous injection of morphine; four hours later, withdrawal was induced by using an opioid antagonist, naloxone. Mice were observed for 30 minutes for the withdrawal signs ie, the characteristic jumping, hyperactivity, urination and diarrhea. ATP-dependent potassium (K+ATP) channel modulators were injected intraperitoneally (i.p.) 30 minutes before the naloxone. It was found that a K+ATP channel opener, minoxidil (12.5–50 mg/kg i.p.), suppressed the morphine withdrawal significantly. On the other hand, the K+ATP channel blocker glibenclamide (12.5–50 mg/kg i.p.) caused a significant facilitation of the withdrawal. Glibenclamide was also found to abolish the minoxidil's inhibitory effect on morphine withdrawal. The study concludes that K+ATP channels play an important role in the genesis of morphine withdrawal and K+ATP channel openers could be useful in the management of opioid withdrawal. As morphine opens K+ATP channels in neurons, the channel openers possibly act by mimicking the effects of morphine on neuronal K+ currents.

scholarly journals Induction of Soil Suppressiveness Against Rhizoctonia solani by Incorporation of Dried Plant Residues into Soil

2006 ◽  
Vol 96 (12) ◽  
pp. 1372-1379 ◽  
Author(s):  
Masahiro Kasuya ◽  
Andriantsoa R. Olivier ◽  
Yoko Ota ◽  
Motoaki Tojo ◽  
Hitoshi Honjo ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Mycelial Growth ◽  
Inhibitory Effect ◽  
Volatile Substance ◽  
Disease Suppression ◽  
Plant Residues ◽  
Infested Soil ◽  
Antagonistic Bacteria ◽  
Damping Off ◽  
Soil Suppressiveness

Suppressive effects of soil amendment with residues of 12 cultivars of Brassica rapa on damping-off of sugar beet were evaluated in soils infested with Rhizoctonia solani. Residues of clover and peanut were tested as noncruciferous controls. The incidence of damping-off was significantly and consistently suppressed in the soils amended with residues of clover, peanut, and B. rapa subsp. rapifera ‘Saori’, but only the volatile substance produced from water-imbibed residue of cv. Saori exhibited a distinct inhibitory effect on mycelial growth of R. solani. Nonetheless, disease suppression in such residue-amended soils was diminished or nullified when antibacterial antibiotics were applied to the soils, suggesting that proliferation of antagonistic bacteria resident to the soils were responsible for disease suppression. When the seed (pericarps) colonized by R. solani in the infested soil without residues were replanted into the soils amended with such residues, damping-off was suppressed in all cases. In contrast, when seed that had been colonized by microorganisms in the soils containing the residues were replanted into the infested soil, damping-off was not suppressed. The evidence indicates that the laimosphere, but not the spermosphere, is the site for the antagonistic microbial interaction, which is the chief principle of soil suppressiveness against Rhizoctonia damping-off.

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