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Salme Timmusk - One of the best experts on this subject based on the ideXlab platform.
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Paenibacillus polymyxa antagonizes oomycete plant pathogens phytophthora palmivora and pythium aphanidermatum
Journal of Applied Microbiology, 2009Co-Authors: Salme Timmusk, Pieter Van West, Neil A. R. Gow, Paul R HuffstutlerAbstract:Aim: To find sustainable alternatives to the application of synthetic chemicals for oomycete pathogen suppression. Methods and Results: Here, we present experiments on an Arabidopsis thaliana model system in which we studied the antagonistic properties of rhizobacterium Paenibacillus polymyxa strains towards the oomycete plant pathogens Phytophthora palmivora and Pythium aphanidermatum. We carried out studies on agar plates, in liquid media and in soil. Our results indicate that P. polymyxa strains significantly reduced P. aphanidermatum and P. palmivora colonization in liquid assays. Most plants that had been treated with P. polymyxa survived the P. aphanidermatum inoculations in soil assays. Conclusions: The antagonistic abilities of both systems correlated well with mycoidal substance production and not with the production of antagonistic substances from the biocontrol bacteria. Significance and Impact of the Study: Our experiments highlight the need to take biofilm formation and niche exclusion mechanisms into consideration for biocontrol assays performed under natural conditions.
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Detection and quantification of Paenibacillus polymyxa in the rhizosphere of wild barley (Hordeum spontaneum) with real-time PCR
Journal of applied microbiology, 2009Co-Authors: Salme Timmusk, Viiu Paalme, U. Lagercrantz, Eviatar NevoAbstract:Aim: To detect and quantify the plant drought tolerance enhancing bacterium Paenibacillus polymyxa in a collection of 160 Hordeum spontaneum rhizosphere samples at the ‘Evolution Canyon’ (‘EC’), Israel. Methods and Results: PCR primers and a FAM-TAMRA probe (6-carboxyfluorescein, 6-carboxy-tetramethyl-rhodamine) targeting 16S rRNA genes were designed and used to detect and quantify the target strain. Two commercial kits, Bio101 Fast Spin and Mo Bio Ultra Clean Soil DNA, were tested for DNA isolation from the rhizosphere and surrounding soil. Population densities of P. polymyxa were studied in the rhizosphere of wild barley and surrounding soil from the contrasting climatic slopes at the ‘EC’ using the real-time PCR and culture based methods. Conclusion: Paenibacillus polymyxa is one of the best established species in wild barley rhizosphere at the ‘EC’ slopes. With the real-time PCR assay we are able to detect 1 pg of DNA per PCR corresponding to 100 cells per ml. The results at the ‘EC’ correlate well to bacterial estimations by culture based methods. Significance and Impact of the Study: Significantly higher P. polymyxa cell number was detected in the rhizosphere of arid ‘African’ microclimate indicating possible role of adaptive co-evolution with plants.
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Paenibacillus polymyxa Invades Plant Roots and Forms Biofilms
Applied and environmental microbiology, 2005Co-Authors: Salme Timmusk, Nina Grantcharova, E. Gerhart H. WagnerAbstract:Paenibacillus polymyxa is a plant growth-promoting rhizobacterium with a broad host range, but so far the use of this organism as a biocontrol agent has not been very efficient. In previous work we showed that this bacterium protects Arabidopsis thaliana against pathogens and abiotic stress (S. Timmusk and E. G. H. Wagner, Mol. Plant-Microbe Interact. 12:951-959, 1999; S. Timmusk, P. van West, N. A. R. Gow, and E. G. H. Wagner, p. 1-28, in Mechanism of action of the plant growth promoting bacterium Paenibacillus polymyxa, 2003). Here, we studied colonization of plant roots by a natural isolate of P. polymyxa which had been tagged with a plasmid-borne gfp gene. Fluorescence microscopy and electron scanning microscopy indicated that the bacteria colonized predominantly the root tip, where they formed biofilms. Accumulation of bacteria was observed in the intercellular spaces outside the vascular cylinder. Systemic spreading did not occur, as indicated by the absence of bacteria in aerial tissues. Studies were performed in both a gnotobiotic system and a soil system. The fact that similar observations were made in both systems suggests that colonization by this bacterium can be studied in a more defined system. Problems associated with green fluorescent protein tagging of natural isolates and deleterious effects of the plant growth-promoting bacteria are discussed.
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Antagonistic effects of Paenibacillus polymyxa towards the oomycete plant pathogens Phytophthora palmivora and Pythium aphanidermatum
2003Co-Authors: Salme Timmusk, Pieter Van West, Neil A. R. Gow, Gerhart E. H. WagnerAbstract:Antagonistic effects of Paenibacillus polymyxa towards the oomycete plant pathogens Phytophthora palmivora and Pythium aphanidermatum
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Mechanism of Action of the Plant Growth Promoting Bacterium Paenibacillus polymyxa
2003Co-Authors: Salme TimmuskAbstract:Paenibacillus polymyxa belongs to the group of plant growth promoting rhizobacteria (PGPR). Activities associated with P. polymyxa-treatment of plants in earlier experiments include, e.g., nitrogen ...
Eviatar Nevo - One of the best experts on this subject based on the ideXlab platform.
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Detection and quantification of Paenibacillus polymyxa in the rhizosphere of wild barley (Hordeum spontaneum) with real-time PCR
Journal of applied microbiology, 2009Co-Authors: Salme Timmusk, Viiu Paalme, U. Lagercrantz, Eviatar NevoAbstract:Aim: To detect and quantify the plant drought tolerance enhancing bacterium Paenibacillus polymyxa in a collection of 160 Hordeum spontaneum rhizosphere samples at the ‘Evolution Canyon’ (‘EC’), Israel. Methods and Results: PCR primers and a FAM-TAMRA probe (6-carboxyfluorescein, 6-carboxy-tetramethyl-rhodamine) targeting 16S rRNA genes were designed and used to detect and quantify the target strain. Two commercial kits, Bio101 Fast Spin and Mo Bio Ultra Clean Soil DNA, were tested for DNA isolation from the rhizosphere and surrounding soil. Population densities of P. polymyxa were studied in the rhizosphere of wild barley and surrounding soil from the contrasting climatic slopes at the ‘EC’ using the real-time PCR and culture based methods. Conclusion: Paenibacillus polymyxa is one of the best established species in wild barley rhizosphere at the ‘EC’ slopes. With the real-time PCR assay we are able to detect 1 pg of DNA per PCR corresponding to 100 cells per ml. The results at the ‘EC’ correlate well to bacterial estimations by culture based methods. Significance and Impact of the Study: Significantly higher P. polymyxa cell number was detected in the rhizosphere of arid ‘African’ microclimate indicating possible role of adaptive co-evolution with plants.
Viiu Paalme - One of the best experts on this subject based on the ideXlab platform.
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Detection and quantification of Paenibacillus polymyxa in the rhizosphere of wild barley (Hordeum spontaneum) with real-time PCR
Journal of applied microbiology, 2009Co-Authors: Salme Timmusk, Viiu Paalme, U. Lagercrantz, Eviatar NevoAbstract:Aim: To detect and quantify the plant drought tolerance enhancing bacterium Paenibacillus polymyxa in a collection of 160 Hordeum spontaneum rhizosphere samples at the ‘Evolution Canyon’ (‘EC’), Israel. Methods and Results: PCR primers and a FAM-TAMRA probe (6-carboxyfluorescein, 6-carboxy-tetramethyl-rhodamine) targeting 16S rRNA genes were designed and used to detect and quantify the target strain. Two commercial kits, Bio101 Fast Spin and Mo Bio Ultra Clean Soil DNA, were tested for DNA isolation from the rhizosphere and surrounding soil. Population densities of P. polymyxa were studied in the rhizosphere of wild barley and surrounding soil from the contrasting climatic slopes at the ‘EC’ using the real-time PCR and culture based methods. Conclusion: Paenibacillus polymyxa is one of the best established species in wild barley rhizosphere at the ‘EC’ slopes. With the real-time PCR assay we are able to detect 1 pg of DNA per PCR corresponding to 100 cells per ml. The results at the ‘EC’ correlate well to bacterial estimations by culture based methods. Significance and Impact of the Study: Significantly higher P. polymyxa cell number was detected in the rhizosphere of arid ‘African’ microclimate indicating possible role of adaptive co-evolution with plants.
U. Lagercrantz - One of the best experts on this subject based on the ideXlab platform.
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Detection and quantification of Paenibacillus polymyxa in the rhizosphere of wild barley (Hordeum spontaneum) with real-time PCR
Journal of applied microbiology, 2009Co-Authors: Salme Timmusk, Viiu Paalme, U. Lagercrantz, Eviatar NevoAbstract:Aim: To detect and quantify the plant drought tolerance enhancing bacterium Paenibacillus polymyxa in a collection of 160 Hordeum spontaneum rhizosphere samples at the ‘Evolution Canyon’ (‘EC’), Israel. Methods and Results: PCR primers and a FAM-TAMRA probe (6-carboxyfluorescein, 6-carboxy-tetramethyl-rhodamine) targeting 16S rRNA genes were designed and used to detect and quantify the target strain. Two commercial kits, Bio101 Fast Spin and Mo Bio Ultra Clean Soil DNA, were tested for DNA isolation from the rhizosphere and surrounding soil. Population densities of P. polymyxa were studied in the rhizosphere of wild barley and surrounding soil from the contrasting climatic slopes at the ‘EC’ using the real-time PCR and culture based methods. Conclusion: Paenibacillus polymyxa is one of the best established species in wild barley rhizosphere at the ‘EC’ slopes. With the real-time PCR assay we are able to detect 1 pg of DNA per PCR corresponding to 100 cells per ml. The results at the ‘EC’ correlate well to bacterial estimations by culture based methods. Significance and Impact of the Study: Significantly higher P. polymyxa cell number was detected in the rhizosphere of arid ‘African’ microclimate indicating possible role of adaptive co-evolution with plants.
Paul R Huffstutler - One of the best experts on this subject based on the ideXlab platform.
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Paenibacillus polymyxa antagonizes oomycete plant pathogens phytophthora palmivora and pythium aphanidermatum
Journal of Applied Microbiology, 2009Co-Authors: Salme Timmusk, Pieter Van West, Neil A. R. Gow, Paul R HuffstutlerAbstract:Aim: To find sustainable alternatives to the application of synthetic chemicals for oomycete pathogen suppression. Methods and Results: Here, we present experiments on an Arabidopsis thaliana model system in which we studied the antagonistic properties of rhizobacterium Paenibacillus polymyxa strains towards the oomycete plant pathogens Phytophthora palmivora and Pythium aphanidermatum. We carried out studies on agar plates, in liquid media and in soil. Our results indicate that P. polymyxa strains significantly reduced P. aphanidermatum and P. palmivora colonization in liquid assays. Most plants that had been treated with P. polymyxa survived the P. aphanidermatum inoculations in soil assays. Conclusions: The antagonistic abilities of both systems correlated well with mycoidal substance production and not with the production of antagonistic substances from the biocontrol bacteria. Significance and Impact of the Study: Our experiments highlight the need to take biofilm formation and niche exclusion mechanisms into consideration for biocontrol assays performed under natural conditions.
