Integration of environmental and host-derived signals with quorum sensing during plant-microbe interactions

Newton, J. A.; Fray, Rupert G.

doi:10.1111/j.1462-5822.2004.00362.x

Cited by 103 publications

(53 citation statements)

References 85 publications

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“…Recently, it has been discovered that certain PGPB quench pathogen quorum-sensing capacity by degrading autoinducer signals, thereby blocking expression of numerous virulence genes (47,48,105,106,113,173). Since most, if not all, bacterial plant pathogens rely upon autoinducer-mediated quorum-sensing to turn on gene cascades for their key virulence factors (e.g., cell-degrading enzymes and phytotoxins) (181), this approach holds tremendous potential for alleviating disease, even after the onset of infection, in a curative manner.…”

Section: Biocontrol Activity Mediated By the Synthesis Of Allelochemimentioning

confidence: 99%

Use of Plant Growth-Promoting Bacteria for Biocontrol of Plant Diseases: Principles, Mechanisms of Action, and Future Prospects

Compant

Duffy

Nowak

et al. 2005

Appl Environ Microbiol

2,137

1,175

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3Pathogenic microorganisms affecting plant health are a major and chronic threat to food production and ecosystem stability worldwide. As agricultural production intensified over the past few decades, producers became more and more dependent on agrochemicals as a relatively reliable method of crop protection helping with economic stability of their operations. However, increasing use of chemical inputs causes several negative effects, i.e., development of pathogen resistance to the applied agents and their nontarget environmental impacts (44, 62). Furthermore, the growing cost of pesticides, particularly in less-affluent regions of the world, and consumer demand for pesticide-free food has led to a search for substitutes for these products. There are also a number of fastidious diseases for which chemical solutions are few, ineffective, or nonexistent (62). Biological control is thus being considered as an alternative or a supplemental way of reducing the use of chemicals in agriculture (44,62,136,188).There has been a large body of literature describing potential uses of plant associated bacteria as agents stimulating plant growth and managing soil and plant health (reviewed in references 63, 70, 143, 165, and 188). Plant growth-promoting bacteria (PGPB) (8) are associated with many, if not all, plant species and are commonly present in many environments. The most widely studied group of PGPB are plant growth-promoting rhizobacteria (PGPR) (82) colonizing the root surfaces and the closely adhering soil interface, the rhizosphere (82, 84). As reviewed by Kloepper et al. (84) or, more recently, by Gray and Smith (65), some of these PGPR can also enter root interior and establish endophytic populations. Many of them are able to transcend the endodermis barrier, crossing from the root cortex to the vascular system, and subsequently thrive as endophytes in stem, leaves, tubers, and other organs (10, 28,65,70). The extent of endophytic colonization of host plant organs and tissues reflects the ability of bacteria to selectively adapt to these specific ecological niches (65, 70). Consequently, intimate associations between bacteria and host plants can be formed (28, 70, 84) without harming the plant (70,83,84,92,191). Although, it is generally assumed that many bacterial endophyte communities are the product of a colonizing process initiated in the root zone (102, 165, 177, 188), they may also originate from other source than the rhizosphere, such as the phyllosphere, the anthosphere, or the spermosphere (70).Despite their different ecological niches, free-living rhizobacteria and endophytic bacteria use some of the same mechanisms to promote plant growth and control phytopathogens (15, 46,63,70,92,165). The widely recognized mechanisms of biocontrol mediated by PGPB are competition for an ecological niche or a substrate, production of inhibitory allelochemicals, and induction of systemic resistance (ISR) in host plants to a broad spectrum of pathogens (15,63,66,67,97,146) and/or abiotic stresses (reviewed in referen...

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Section: Biocontrol Activity Mediated By the Synthesis Of Allelochemimentioning

confidence: 99%

Use of Plant Growth-Promoting Bacteria for Biocontrol of Plant Diseases: Principles, Mechanisms of Action, and Future Prospects

Compant

Duffy

Nowak

et al. 2005

Appl Environ Microbiol

2,137

1,175

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show abstract

“…Often, the regulated genes are crucial to the colonization or infection of the eukaryotic hosts (6,7). Local conditions on a microscopic scale (such as pH, enclosed environment, and diffusion characteristics) may affect signal molecule longevity, stability, and accumulation, which could be used to provide information in addition to population density (8).…”

mentioning

confidence: 99%

Quorum signal molecules as biosurfactants affecting swarming in Rhizobium etli

Daniels

Reynaert

Hoekstra

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

141

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Swarming motility is suggested to be a social phenomenon that enables groups of bacteria to coordinately and rapidly move atop solid surfaces. This multicellular behavior, during which the apparently organized bacterial populations are embedded in an extracellular slime layer, has previously been linked with biofilm formation and virulence. Many population density-controlled activities involve the activation of complex signaling pathways using small diffusible molecules, also known as autoinducers. In Gramnegative bacteria, quorum sensing (QS) is achieved primarily by means of N-acylhomoserine lactones (AHLs). Here, we report on a dual function of AHL molecules in controlling swarming behavior of Rhizobium etli, the bacterial symbiotic partner of the common bean plant. The major swarming regulator of R. etli is the cinIR QS system, which is specifically activated in swarming cells by its cognate AHL and other long-chain AHLs. This signaling role of long-chain AHLs is required for high-level expression of the cin and rai QS systems. Besides this signaling function, the long-chain AHLs also have a direct role in surface movement of swarmer cells as these molecules possess significant surface activity and induce liquid flows, known as Marangoni flows, as a result of gradients in surface tension at biologically relevant concentrations. These results point to an as-yet-undisclosed direct role of long-chain AHL molecules as biosurfactants.cell-cell signaling ͉ motility ͉ quorum sensing

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“…Understanding autoinduction in pathogenic bacteria enables us to pursue signal inactivation or degradation as a new approach to sustainable disease control (35). A few plant and microbial compounds, such as AHL-degrading proteins produced by rhizosphere bacteria, have been reported to have such activity against AHLs (43).…”

mentioning

confidence: 99%

Autoinduction in Erwinia amylovora : Evidence of an Acyl-Homoserine Lactone Signal in the Fire Blight Pathogen

Molina¹,

Rezzonico²,

Défago³

et al. 2005

J Bacteriol

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Erwinia amylovora causes fire blight disease of apple, pear, and other members of the Rosaceae. Here we present the first evidence for autoinduction in E. amylovora and a role for an N-acyl-homoserine lactone (AHL)-type signal. Two major plant virulence traits, production of extracellular polysaccharides (amylovoran and levan) and tolerance to free oxygen radicals, were controlled in a bacterial-cell-density-dependent manner. Two standard autoinducer biosensors, Agrobacterium tumefaciens NTL4 and Vibrio harveyi BB886, detected AHL in stationary-phase cultures of E. amylovora. A putative AHL synthase gene, eamI, was partially sequenced, which revealed homology with autoinducer genes from other bacterial pathogens (e.g., carI, esaI, expI, hsII, yenI, and luxI). E. amylovora was also found to carry eamR, a convergently transcribed gene with homology to luxR AHL activator genes in pathogens such as Erwinia carotovora. Heterologous expression of the Bacillus sp. strain A24 acyl-homoserine lactonase gene aiiA in E. amylovora abolished induction of AHL biosensors, impaired extracellular polysaccharide production and tolerance to hydrogen peroxide, and reduced virulence on apple leaves.

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Integration of environmental and host-derived signals with quorum sensing during plant-microbe interactions

Cited by 103 publications

References 85 publications

Use of Plant Growth-Promoting Bacteria for Biocontrol of Plant Diseases: Principles, Mechanisms of Action, and Future Prospects

Use of Plant Growth-Promoting Bacteria for Biocontrol of Plant Diseases: Principles, Mechanisms of Action, and Future Prospects

Quorum signal molecules as biosurfactants affecting swarming in Rhizobium etli

Autoinduction in Erwinia amylovora : Evidence of an Acyl-Homoserine Lactone Signal in the Fire Blight Pathogen

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