Activation of systemic acquired disease resistance in plants

Keßmann, Helmut; Staub, T.; Ligón, James M.; Oostendorp, M.; Ryals, John

doi:10.1007/bf01874804

Cited by 83 publications

(43 citation statements)

References 55 publications

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“…However, since the OA^ mutant colonized internal root tissues less frequently, it consequently induced the localized wall responses less frequently. Such a localized cell response might trigger the systemic resistance response in plants (Kessmann et al, 1994), which would in turn be weaker with the OA^ mutant B4 than in plants treated with wild-type strain WCS417r. Further studies on the relation between the observed localized responses of the tomato root tissue and systemic resistance induced by root colonization with strain WCS417r should elucidate this proposed type of acquired resistance.…”

Section: Discussionmentioning

confidence: 99%

Involvement of the outer membrane lipopolysaccharides in the endophytic colonization of tomato roots by biocontrol Pseudomonas fluorescens strain WCS417r

1997

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SUMMARYPrevious studies demonstrated the role of the O-antigenic side chain of the outer membrane lipopolysaccharides of Pseudomonas fluorescens strain WCS417r in its ability to induce resistance against fusarium wilt disease. The present study compared the colonization of tomato roots {Lycopersicon esculentum Mill.) by P. fluorescens strain WCS417r with that of a mutant of this strain, lacking the O-antigenic side chain of its outer membrane lipopolysaccharides (OA"). Special attention was paid to colonization within root tissues and changes of the root ultrastructure induced by the bacterial strains. Experiments were performed with tomato plants rooted in rock wool and tomato seedlings grown on agar. Numeration of colony-forming units showed that wild-type stram WCS417r colonized the root interior of tomato grown in rock wool to a higher extent than its OA"^ mutant B4, whereas colonization of the rhizoplane did not differ between the two. Light microscopy observations of cross sections of roots grown on agar showed that (i) colonization of the root interior by both wild-type and O A" mutant was inter-and intracellular, (ii) colonization of the internal root tissues mainly occurred if the Pseudomonas strains were inoculated at sites of lateral root emergence, (iii) the wild type colonized the root interior more frequently than did its OA" mutant. Thickening of the cortical cell walls, in reaction to the bacterial colonization of epidermal or hypodermal cells, or cortical intercellular spaces, suggested that local defence reactions of the plant occurred. Altogether, these results indicate the involvement of the O-antigenic side chain of the outer membrane lipopolysaccharides in the endophytic colonization of the tomato root by P. fluorescens, WCS417r, and lead us to hypothesize that induction of disease resistance by strain WCS417r might be related to the extent of colonization of the internal root tissues.

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Section: Discussionmentioning

confidence: 99%

Involvement of the outer membrane lipopolysaccharides in the endophytic colonization of tomato roots by biocontrol Pseudomonas fluorescens strain WCS417r

1997

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“…Induction of SAR by SA is associated with the accumulation of PRs (38,95,97). At least eight of the ten major PRs induced in tobacco in response to pathogens causing hypersensitive necrosis, were found in the intercellular washing fluid (IWF) of leaves of plants grown in autoclaved soil in the presence of P. fluorescens CHA0, which is likely to produce SA in the rhizosphere (67).…”

Section: Induced Systemic Resistance Is Generally Not Associated Withmentioning

confidence: 99%

“…SAR is characterized by an accumulation of salicylic acid (SA) and pathogenesis-related proteins (PRs) (38,82,89,95,102). Accumulation of SA occurs both locally and, at lower levels, systemically, concomitant with the development of SAR.…”

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confidence: 99%

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Systemic Resistance Induced by Rhizosphere Bacteria

Loon

Bakker

Pieterse

1998

Annu. Rev. Phytopathol.

1,987

1,108

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Nonpathogenic rhizobacteria can induce a systemic resistance in plants that is phenotypically similar to pathogen-induced systemic acquired resistance (SAR). Rhizobacteria-mediated induced systemic resistance (ISR) has been demonstrated against fungi, bacteria, and viruses in Arabidopsis, bean, carnation, cucumber, radish, tobacco, and tomato under conditions in which the inducing bacteria and the challenging pathogen remained spatially separated. Bacterial strains differ in their ability to induce resistance in different plant species, and plants show variation in the expression of ISR upon induction by specific bacterial strains.

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“…The enhanced defensive capacity characteristic of SAR is always associated with the accumulation of PRs. Notably, PR-1 is commonly taken as a marker that SAR has been induced (Kessmann et al 1994). In Arabidopsis, SA-dependent SAR is typically associated with the activation of three PR genes: PR-1, -2 and -5.…”

Section: Signalling Pathways Of Systemically Induced Resistancementioning

confidence: 99%

Plant responses to plant growth-promoting rhizobacteria

2007

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Non-pathogenic soilborne microorganisms can promote plant growth, as well as suppress diseases. Plant growth promotion is taken to result from improved nutrient acquisition or hormonal stimulation. Disease suppression can occur through microbial antagonism or induction of resistance in the plant. Several rhizobacterial strains have been shown to act as plant growth-promoting bacteria through both stimulation of growth and induced systemic resistance (ISR), but it is not clear in how far both mechanisms are connected. Induced resistance is manifested as a reduction of the number of diseased plants or in disease severity upon subsequent infection by a pathogen. Such reduced disease susceptibility can be local or systemic, result from developmental or environmental factors and depend on multiple mechanisms. The spectrum of diseases to which PGPRelicited ISR confers enhanced resistance overlaps partly with that of pathogen-induced systemic acquired resistance (SAR). Both ISR and SAR represent a state of enhanced basal resistance of the plant that depends on the signalling compounds jasmonic acid and salicylic acid, respectively, and pathogens are differentially sensitive to the resistances activated by each of these signalling pathways. Root-colonizing Pseudomonas bacteria have been shown to alter plant gene expression in roots and leaves to different extents, indicative of recognition of one or more bacterial determinants by specific plant receptors. Conversely, plants can alter root exudation and secrete compounds that interfere with quorum sensing (QS) regulation in the bacteria. Such two-way signalling resembles the interaction of root-nodulating Rhizobia with legumes and between mycorrhizal fungi and roots of the majority of plant species. Although ISR-eliciting rhizobacteria can induce typical early defence-related responses in cell suspensions, in plants they do not necessarily activate defence-related gene expression. Instead, they appear to act through priming of effective resistance mechanisms, as reflected by earlier and stronger defence reactions once infection occurs.

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Activation of systemic acquired disease resistance in plants

Cited by 83 publications

References 55 publications

Involvement of the outer membrane lipopolysaccharides in the endophytic colonization of tomato roots by biocontrol Pseudomonas fluorescens strain WCS417r

Involvement of the outer membrane lipopolysaccharides in the endophytic colonization of tomato roots by biocontrol Pseudomonas fluorescens strain WCS417r

Systemic Resistance Induced by Rhizosphere Bacteria

Plant responses to plant growth-promoting rhizobacteria

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