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L.c. Van Loon - One of the best experts on this subject based on the ideXlab platform.
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Induced Systemic Resistance by Fluorescent Pseudomonas spp.
Phytopathology, 2007Co-Authors: Peter A. H. M. Bakker, Corné M. J. Pieterse, L.c. Van LoonAbstract:ABSTRACT Fluorescent Pseudomonas spp. have been studied for decades for their plant growth-promoting effects through effective suppression of soilborne plant diseases. The modes of action that play a role in disease suppression by these bacteria include siderophore-mediated competition for iron, antibiosis, production of lytic enzymes, and induced Systemic Resistance (ISR). The involvement of ISR is typically studied in systems in which the Pseudomonas bacteria and the pathogen are inoculated and remain spatially separated on the plant, e.g., the bacteria on the root and the pathogen on the leaf, or by use of split root systems. Since no direct interactions are possible between the two populations, suppression of disease development has to be plant-mediated. In this review, bacterial traits involved in Pseudomonas-mediated ISR will be discussed.
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Induced Systemic Resistance as a Mechanism of Disease Suppression by Rhizobacteria
PGPR: Biocontrol and Biofertilization, 2005Co-Authors: L.c. Van Loon, Peter A. H. M. BakkerAbstract:Plant growth-promoting rhizobacteria can suppress diseases through antagonism between the bacteria and soil-borne pathogens, as well as by inducing a Systemic Resistance in the plant against both root and foliar pathogens. The generally non-specific character of induced Resistance constitutes an increase in the level of basal Resistance to several pathogens simultaneously, which is of benefit under natural conditions where multiple pathogens may be present. Specific Pseudomonas strains induce Systemic Resistance in e.g. carnation, cucumber, radish, tobacco and Arabidopsis, as evidenced by an enhanced defensive capacity upon challenge inoculation. Although some bacterial strains are equally effective in inducing Resistance in different plant species, others show specificity, indicating specific recognition between bacteria and plants at the root surface. In carnation, radish and Arabidopsis, the O-antigenic side chain of the bacterial outer membrane lipopolysaccharide acts as an inducing determinant, but other bacterial traits are also involved. Pseudobactin siderophores have been implicated in the induction of Resistance in tobacco and Arabidopsis, and another siderophore, pseudomonine, may explain induction of Resistance associated with salicylic acid (SA) in radish. Although SA induces phenotypically similar Systemic acquired Resistance (SAR), it is not necessary for the Systemic Resistance induced by most rhizobacterial strains. Instead, rhizobacteria-mediated induced Systemic Resistance (ISR) is dependent on jasmonic acid (JA) and ethylene signaling in the plant. Upon challenge inoculation of induced Arabidopsis plants with a pathogen, leaves expressing SAR exhibit a primed expression of SA-, but not JA/ethylene-responsive defense-related genes, whereas leaves expressing ISR are primed to express JA/ethylene-, but not SA-responsive genes. Combination of ISR and SAR can increase protection against pathogens that are resisted through both pathways, as well as extend protection to a broader spectrum of pathogens than ISR or SAR alone.
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No role for bacterially produced salicylic Acid in rhizobacterial induction of Systemic Resistance in Arabidopsis.
Phytopathology, 2005Co-Authors: L. X. Ran, L.c. Van Loon, Peter A. H. M. BakkerAbstract:ABSTRACT The role of bacterially produced salicylic acid (SA) in the induction of Systemic Resistance in plants by rhizobacteria is far from clear. The strong SA producer Pseudomonas fluorescens WCS374r induces Resistance in radish but not in Arabidopsis thaliana, whereas application of SA leads to induction of Resistance in both plant species. In this study, we compared P. fluorescens WCS374r with three other SA-producing fluorescent Pseudomonas strains, P. fluorescens WCS417r and CHA0r, and P. aeruginosa 7NSK2 for their abilities to produce SA under different growth conditions and to induce Systemic Resistance in A. thaliana against bacterial speck, caused by P. syringae pv. tomato. All strains produced SA in vitro, varying from 5 fg cell(-1) for WCS417r to >25 fg cell(-1) for WCS374r. Addition of 200 muM FeCl(3) to standard succinate medium abolished SA production in all strains. Whereas the incubation temperature did not affect SA production by WCS417r and 7NSK2, strains WCS374r and CHA0r produced more SA when grown at 33 instead of 28 degrees C. WCS417r, CHA0r, and 7NSK2 induced Systemic Resistance apparently associated with their ability to produce SA, but WCS374r did not. Conversely, a mutant of 7NSK2 unable to produce SA still triggered induced Systemic Resistance (ISR). The possible involvement of SA in the induction of Resistance was evaluated using SA-nonaccumulating transgenic NahG plants. Strains WCS417r, CHA0r, and 7NSK2 induced Resistance in NahG Arabidopsis. Also, WCS374r, when grown at 33 or 36 degrees C, triggered ISR in these plants, but not in ethylene-insensitive ein2 or in non-plant pathogenesis- related protein-expressing npr1 mutant plants, irrespective of the growth temperature of the bacteria. These results demonstrate that, whereas WCS374r can be manipulated to trigger ISR in Arabidopsis, SA is not the primary determinant for the induction of Systemic Resistance against bacterial speck disease by this bacterium. Also, for the other SAproducing strains used in this study, bacterial determinants other than SA must be responsible for inducing Resistance.
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Signaling during rhizobacteria-induced Systemic Resistance in Arabidopsis
2004Co-Authors: Corné M. J. Pieterse, Peter A. H. M. Bakker, B.w.m. Verhagen, L.c. Van LoonAbstract:Arabidopsis plants of which the roots are colonized by specific strains of non-pathogenic fluorescent Pseudomonas bacteria develop an induced Systemic Resistance (ISR) that, unlike pathogen- induced Systemic acquired Resistance (SAR), is independent of salicylic acid (SA) but requires sensitivity to jasmonic acid (JA) and ethylene (ET). Various Pseudomonas spp. strains induce broad-spectrum disease Resistance in plants in a bacterial strain/plant species-specific manner. Different bacterial determinants appear to be involved in triggering ISR, e.g. lipopolysaccharides (LPS), siderophores, flagella and antibiotics. Combining ISR and SAR increased Resistance against pathogens that are resisted by both JA/ET- and SA-dependent defenses, but not against pathogens that are affected exclusively by either ISR or SAR. Unlike SAR, the onset of ISR is not associated with major changes in gene expression, but upon challenge inoculation ISR-expressing plants are primed to express certain sets of genes more quickly and/or at higher levels.
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Understanding the involvement of rhizobacteria-mediated induction of Systemic Resistance in biocontrol of plant diseases
Canadian Journal of Plant Pathology, 2003Co-Authors: Peter A. H. M. Bakker, Corné M. J. Pieterse, L. X. Ran, L.c. Van LoonAbstract:Specific strains of nonpathogenic rhizobacteria can induce Systemic Resistance that is effective against a range of plant pathogens. To exploit induced Systemic Resistance, detailed knowledge of the triggering bacterial traits involved and on signal transduction pathways in the plant is necessary. Possibilities to improve effectiveness of induced Resistance by rhizobacterial strains are discussed.
Corné M. J. Pieterse - One of the best experts on this subject based on the ideXlab platform.
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Induced Systemic Resistance by beneficial microbes
Annual review of phytopathology, 2014Co-Authors: Corné M. J. Pieterse, Christos Zamioudis, Roeland L. Berendsen, David M. Weller, Saskia C. M. Van Wees, Peter A. H. M. BakkerAbstract:Beneficial microbes in the microbiome of plant roots improve plant health. Induced Systemic Resistance (ISR) emerged as an important mechanism by which selected plant growth–promoting bacteria and fungi in the rhizosphere prime the whole plant body for enhanced defense against a broad range of pathogens and insect herbivores. A wide variety of root-associated mutualists, including Pseudomonas, Bacillus, Trichoderma, and mycorrhiza species sensitize the plant immune system for enhanced defense without directly activating costly defenses. This review focuses on molecular processes at the interface between plant roots and ISR-eliciting mutualists, and on the progress in our understanding of ISR signaling and Systemic defense priming. The central role of the root-specific transcription factor MYB72 in the onset of ISR and the role of phytohormones and defense regulatory proteins in the expression of ISR in aboveground plant parts are highlighted. Finally, the ecological function of ISR-inducing microbes in the root microbiome is discussed.
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Induced Systemic Resistance and the rhizosphere microbiome.
The plant pathology journal, 2013Co-Authors: Peter A. H. M. Bakker, Rogier F. Doornbos, Christos Zamioudis, Roeland L. Berendsen, Corné M. J. PieterseAbstract:Microbial communities that are associated with plant roots are highly diverse and harbor tens of thousands of species. This so-called microbiome controls plant health through several mechanisms including the suppression of infectious diseases, which is especially prominent in disease suppressive soils. The mechanisms implicated in disease suppression include competition for nutrients, antibiosis, and induced Systemic Resistance (ISR). For many biological control agents ISR has been recognized as the mechanism that at least partly explains disease suppression. Implications of ISR on recruitment and functioning of the rhizosphere microbiome are discussed.
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Bacterial elicitors and plant signaling in induced Systemic Resistance.
2008Co-Authors: Peter A. H. M. Bakker, J.a. Van Pelt, I. Van Der Sluis, Corné M. J. PieterseAbstract:Plant root colonizing, fluorescent Pseudomonas spp. have been studied for decades for their plant growth promoting properties and their effective suppression of soil borne plant diseases. The modes of action that play a role in disease suppression by these bacteria include siderophore-mediated competition for iron, antibiosis, and induced Systemic Resistance (ISR). The involvement of ISR is typically studied in systems in which the Pseudomonas bacteria and the pathogen are inoculated and remain spatially separated on the plant, e.g. the bacteria on the root and the pathogen on the leaf, or the use of split root systems. Since no direct interactions are possible between the two populations, suppression of disease development has to be plant mediated. We discuss bacterial traits and the plant signal transduction pathways involved in Pseudomonas mediated ISR, in particular in the model plant Arabidopsis thaliana.
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Induced Systemic Resistance by Fluorescent Pseudomonas spp.
Phytopathology, 2007Co-Authors: Peter A. H. M. Bakker, Corné M. J. Pieterse, L.c. Van LoonAbstract:ABSTRACT Fluorescent Pseudomonas spp. have been studied for decades for their plant growth-promoting effects through effective suppression of soilborne plant diseases. The modes of action that play a role in disease suppression by these bacteria include siderophore-mediated competition for iron, antibiosis, production of lytic enzymes, and induced Systemic Resistance (ISR). The involvement of ISR is typically studied in systems in which the Pseudomonas bacteria and the pathogen are inoculated and remain spatially separated on the plant, e.g., the bacteria on the root and the pathogen on the leaf, or by use of split root systems. Since no direct interactions are possible between the two populations, suppression of disease development has to be plant-mediated. In this review, bacterial traits involved in Pseudomonas-mediated ISR will be discussed.
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Signaling during rhizobacteria-induced Systemic Resistance in Arabidopsis
2004Co-Authors: Corné M. J. Pieterse, Peter A. H. M. Bakker, B.w.m. Verhagen, L.c. Van LoonAbstract:Arabidopsis plants of which the roots are colonized by specific strains of non-pathogenic fluorescent Pseudomonas bacteria develop an induced Systemic Resistance (ISR) that, unlike pathogen- induced Systemic acquired Resistance (SAR), is independent of salicylic acid (SA) but requires sensitivity to jasmonic acid (JA) and ethylene (ET). Various Pseudomonas spp. strains induce broad-spectrum disease Resistance in plants in a bacterial strain/plant species-specific manner. Different bacterial determinants appear to be involved in triggering ISR, e.g. lipopolysaccharides (LPS), siderophores, flagella and antibiotics. Combining ISR and SAR increased Resistance against pathogens that are resisted by both JA/ET- and SA-dependent defenses, but not against pathogens that are affected exclusively by either ISR or SAR. Unlike SAR, the onset of ISR is not associated with major changes in gene expression, but upon challenge inoculation ISR-expressing plants are primed to express certain sets of genes more quickly and/or at higher levels.
Peter A. H. M. Bakker - One of the best experts on this subject based on the ideXlab platform.
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Induced Systemic Resistance by beneficial microbes
Annual review of phytopathology, 2014Co-Authors: Corné M. J. Pieterse, Christos Zamioudis, Roeland L. Berendsen, David M. Weller, Saskia C. M. Van Wees, Peter A. H. M. BakkerAbstract:Beneficial microbes in the microbiome of plant roots improve plant health. Induced Systemic Resistance (ISR) emerged as an important mechanism by which selected plant growth–promoting bacteria and fungi in the rhizosphere prime the whole plant body for enhanced defense against a broad range of pathogens and insect herbivores. A wide variety of root-associated mutualists, including Pseudomonas, Bacillus, Trichoderma, and mycorrhiza species sensitize the plant immune system for enhanced defense without directly activating costly defenses. This review focuses on molecular processes at the interface between plant roots and ISR-eliciting mutualists, and on the progress in our understanding of ISR signaling and Systemic defense priming. The central role of the root-specific transcription factor MYB72 in the onset of ISR and the role of phytohormones and defense regulatory proteins in the expression of ISR in aboveground plant parts are highlighted. Finally, the ecological function of ISR-inducing microbes in the root microbiome is discussed.
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Induced Systemic Resistance and the rhizosphere microbiome.
The plant pathology journal, 2013Co-Authors: Peter A. H. M. Bakker, Rogier F. Doornbos, Christos Zamioudis, Roeland L. Berendsen, Corné M. J. PieterseAbstract:Microbial communities that are associated with plant roots are highly diverse and harbor tens of thousands of species. This so-called microbiome controls plant health through several mechanisms including the suppression of infectious diseases, which is especially prominent in disease suppressive soils. The mechanisms implicated in disease suppression include competition for nutrients, antibiosis, and induced Systemic Resistance (ISR). For many biological control agents ISR has been recognized as the mechanism that at least partly explains disease suppression. Implications of ISR on recruitment and functioning of the rhizosphere microbiome are discussed.
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Pseudomonas putida KT2440 causes induced Systemic Resistance and changes in Arabidopsis root exudation
Environmental microbiology reports, 2009Co-Authors: Miguel A. Matilla, Peter A. H. M. Bakker, Rogier F. Doornbos, Juan L. Ramos, Dayakar V. Badri, Jorge M. Vivanco, María Isabel Ramos-gonzálezAbstract:Summary Pseudomonas putida KT2440 is an efficient colonizer of the rhizosphere of plants of agronomical and basic interest. We have demonstrated that KT2440 can protect the model plant Arabidopsis thaliana against infection by the phytopathogen Pseudomonas syrin- gae pv. tomato DC3000. P. putida extracellular haem- peroxidase (PP2561) was found to be important for competitive colonization and essential for the induc- tion of plant Systemic Resistance. Root exudates of plants elicited by KT2440 exhibited distinct patterns of metabolites compared with those of non-elicited plants. The levels of some of these compounds were dramatically reduced in axenic plants or plants colo- nized by a mutant defective in PP2561, which has increased sensitiveness to oxidative stress with respect to the wild type. Thus high-level oxidative stress Resistance is a bacterial driving force in the rhizosphere for efficient colonization and to induce Systemic Resistance. These results provide important new insight into the complex events that occur in order for plants to attain Resistance against foliar pathogens.
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Bacterial elicitors and plant signaling in induced Systemic Resistance.
2008Co-Authors: Peter A. H. M. Bakker, J.a. Van Pelt, I. Van Der Sluis, Corné M. J. PieterseAbstract:Plant root colonizing, fluorescent Pseudomonas spp. have been studied for decades for their plant growth promoting properties and their effective suppression of soil borne plant diseases. The modes of action that play a role in disease suppression by these bacteria include siderophore-mediated competition for iron, antibiosis, and induced Systemic Resistance (ISR). The involvement of ISR is typically studied in systems in which the Pseudomonas bacteria and the pathogen are inoculated and remain spatially separated on the plant, e.g. the bacteria on the root and the pathogen on the leaf, or the use of split root systems. Since no direct interactions are possible between the two populations, suppression of disease development has to be plant mediated. We discuss bacterial traits and the plant signal transduction pathways involved in Pseudomonas mediated ISR, in particular in the model plant Arabidopsis thaliana.
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Induced Systemic Resistance by Fluorescent Pseudomonas spp.
Phytopathology, 2007Co-Authors: Peter A. H. M. Bakker, Corné M. J. Pieterse, L.c. Van LoonAbstract:ABSTRACT Fluorescent Pseudomonas spp. have been studied for decades for their plant growth-promoting effects through effective suppression of soilborne plant diseases. The modes of action that play a role in disease suppression by these bacteria include siderophore-mediated competition for iron, antibiosis, production of lytic enzymes, and induced Systemic Resistance (ISR). The involvement of ISR is typically studied in systems in which the Pseudomonas bacteria and the pathogen are inoculated and remain spatially separated on the plant, e.g., the bacteria on the root and the pathogen on the leaf, or by use of split root systems. Since no direct interactions are possible between the two populations, suppression of disease development has to be plant-mediated. In this review, bacterial traits involved in Pseudomonas-mediated ISR will be discussed.
Monica Hofte - One of the best experts on this subject based on the ideXlab platform.
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The cyclic lipopeptide orfamide induces Systemic Resistance in rice to Cochliobolus miyabeanus but not to Magnaporthe oryzae
Plant cell reports, 2017Co-Authors: Marc Ongena, Monica HofteAbstract:Key message The Pseudomonas- derived cyclic lipopeptide orfamide can induce Resistance to Cochliobolus miyabeanus but not to Magnaporthe oryzae in rice. Abscisic acid signaling is involved in the induced Systemic Resistance response triggered by orfamide.
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Role of phenazines and cyclic lipopeptides produced by pseudomonas sp. CMR12a in induced Systemic Resistance on rice and bean
Environmental microbiology reports, 2016Co-Authors: Gia Khuong Hoang Hua, Marc Ongena, Monica HofteAbstract:Pseudomonas sp. CMR12a produces two different classes of cyclic lipopeptides (CLPs) (orfamides and sessilins), which all play a role in direct antagonism against soilborne pathogens. Here we show that Pseudomonas sp. CMR12a is also able to induce Systemic Resistance to Magnaporthe oryzae on rice and to the web blight pathogen Rhizoctonia solani AG2-2 on bean. Plant assays with biosynthesis mutants of Pseudomonas sp. CMR12a impaired in the production of phenazines and/or CLPs and purified metabolites revealed that distinct bacterial determinants are responsible for inducing Systemic Resistance in these two pathosystems. In rice, mutants impaired in phenazine production completely lost their ability to induce Systemic Resistance, while a soil drench with pure phenazine-1-carboxamide (PCN) at a concentration of 0.1 or 1 μM was active in inducing Resistance against M. oryzae. In bean, mutants that only produced phenazines, sessilins or orfamides were still able to induce Systemic Resistance against Rhizoctonia web blight, but a balanced production of these metabolites was needed. This study not only shows that Pseudomonas sp. CMR12a can protect rice to blast disease and bean to web blight disease, but also displays that the determinants involved in induced Systemic Resistance are plant, pathogen and concentration dependent.
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Determinants of Pseudomonas putida WCS358 involved in inducing Systemic Resistance in plants
Molecular plant pathology, 2005Co-Authors: Hamid Meziane, Monica Hofte, Ientse Van Der Sluis, Leendert C. Van Loon, Peter A. H. M. BakkerAbstract:SUMMARY Pseudomonas putida WCS358 is a plant growth-promoting rhizobacterium originally isolated from the rhizosphere of potato. It can suppress soil-borne plant diseases by siderophore-mediated competition for iron, but it has also been reported to result in induced Systemic Resistance (ISR) in Arabidopsis thaliana . Bacterial determinants of this strain involved in inducing Systemic Resistance in Arabidopsis were investigated using a Tn 5 transposon mutant defective in biosynthesis of the fluorescent siderophore pseudobactin, a non-motile Tn 5 mutant lacking flagella, and a spontaneous phage-resistant mutant lacking the O-antigenic side chain of the lipopolysaccharides (LPS). When using Pseudomonas syringae pv. tomato as the challenging pathogen, purified pseudobactin, flagella and LPS all triggered ISR. However, the mutants were all as effective as the parental strain, suggesting redundancy in ISR-triggering traits in WCS358. The Botrytis cinerea ‐ tomato, B. cinerea ‐bean and Colletotrichum lindemuthianum ‐bean model systems were used to test further the potential of P. putida WCS358 to induce ISR. Strain WCS358 significantly reduced disease development in all three systems, indicating that also on tomato and bean WCS358 can trigger ISR. In both tomato and bean, the LPS mutant had lost the ability to induce Resistance, whereas the flagella mutant was still effective. In bean, the pseudobactin mutant was still effective, whereas this mutant has lost its effectivity in tomato. In both bean and tomato, flagella isolated from the parental strain were not effective, whereas LPS or pseudobactin did induce Systemic Resistance.
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Induced Systemic Resistance in Trichoderma harzianum T39 biocontrol of Botrytis cinerea
European Journal of Plant Pathology, 1998Co-Authors: Geert De Meyer, Yigal Elad, Joseph Bigirimana, Monica HofteAbstract:Biocontrol of Botrytis cinerea with Trichoderma spp. is generally believed to result from direct interaction of the biocontrol agent with the pathogen or from a Trichoderma-induced change in environmental conditions that affects B. cinerea development. In this work we provide arguments for the participation of induced plant defence in T. harzianum T39 control of B. cinerea. In tomato, lettuce, pepper, bean and tobacco, T. harzianum T39 application at sites spatially separated from the B. cinerea inoculation resulted in a 25–100%percnt; reduction of grey mould symptoms, caused by a delay or suppression of spreading lesion formation. Given the spatial separation of both micro-organisms, this effect was attributed to the induction of Systemic Resistance by T. harzianum T39. The observation that in bean the effect of T. harzianum T39 was similar to that of the rhizobacterium Pseudomonas aeruginosa KMPCH, a reference strain for the induction of Systemic Resistance, confirmed this hypothesis. Since B. cinerea control on tobacco leaves sprayed with T. harzianum T39 was similar to the control on leaves from T. harzianum T39 soil-treated plants, induction of plant defence might also participate in biocontrol on treated leaves.
Xuewen Gao - One of the best experts on this subject based on the ideXlab platform.
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Effect of volatile compounds produced by Ralstonia solanacearum on plant growth promoting and Systemic Resistance inducing potential of Bacillus volatiles.
BMC plant biology, 2017Co-Authors: Hafiz Abdul Samad Tahir, Waseem Raza, Asma Safdar, Ziyang Huang, Faheem Uddin Rajer, Xuewen GaoAbstract:Microbial volatiles play an expedient role in the agricultural ecological system by enhancing plant growth and inducing Systemic Resistance against plant pathogens, without causing hazardous effects on the environment. To explore the effects of VOCs of Ralstonia solanacearum TBBS1 (Rs) on tobacco plant growth and on plant growth promoting efficiency of VOCs produced by Bacillus subtilis SYST2, experiments were conducted both in vitro and in planta. The VOCs produced by SYST2 significantly enhanced the plant growth and induced the Systemic Resistance (ISR) against wilt pathogen Rs in all experiments. The SYST2-VOCs significantly increased PPO and PAL activity and over-expressed the genes relating to expansin, wilt Resistance, and plant defense while repressed the genes relating to ethylene production. More interestingly, VOCs produced by pathogen, Rs had no significant effect on plant growth; however, Rs-VOCs decreased the growth promoting potential of SYST2-VOCs when plants were exposed to VOCs produced by both SYST2 and Rs. The co-culture of SYST2 and Rs revealed that they inhibited the growth of each other; however, the inhibition of Rs by SYST2-VOCs appeared to be greater than that of SYST2 by Rs-VOCs. Our findings provide new insights regarding the interaction among SYST2-VOCs, Rs-VOCs and plant, resulting in growth promotion and induced Systemic Resistance against the bacterial wilt pathogen Rs. This is the first report of the effect of VOCs produced by pathogenic microorganism on plant growth and on plant growth-promoting and Systemic Resistance-inducing potential of PGPR strain SYST2.
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Molecular Mechanism of Plant Growth Promotion and Induced Systemic Resistance to Tobacco Mosaic Virus by Bacillus spp.
Journal of microbiology and biotechnology, 2009Co-Authors: Shuai Wang, Junqing Qiao, Jun Liu, Yanfei Xia, Xuewen GaoAbstract:Bacillus spp., as a type of plant growth-promoting rhizobacteria (PGPR), were studied with regards promoting plant growth and inducing plant Systemic Resistance. The results of greenhouse experiments with tobacco plants demonstrated that treatment with the Bacillus spp. significantly enhanced the plant height and fresh weight, while clearly lowering the disease severity rating of the tobacco mosaic virus (TMV) at 28 days post-inoculation (dpi). The TMV accumulation in the young non-inoculated leaves was remarkably lower for all the plants treated with the Bacillus spp. An RTPCR analysis of the signaling regulatory genes Coi1 and NPR1, and defense genes PR-1a and PR-1b, in the tobacco treated with the Bacillus spp. revealed an association with enhancing the Systemic Resistance of tobacco to TMV. A further analysis of two expansin genes that regulate plant cell growth, NtEXP2 and NtEXP6, also verified a concomitant growth promotion in the roots and leaves of the tobacco responding to Bacillus spp.
