Colonization of the rhizosphere of crop plants by plant-beneficial pseudomonads

Weger, Letty A. de; Bij, Arjan J. van der; Dekkers, Linda C.; Simons, Marco; Wijffelman, C. A.; Lugtenberg, Ben

doi:10.1111/j.1574-6941.1995.tb00146.x

Cited by 97 publications

(18 citation statements)

References 24 publications

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“…The closely packed structure of the epidermis in this part of the root (Foster, Rovira & Cock, 1983) probably forms a barrier for the bacteria to enter. Bacterial cell-surface components like the Oantigenic side chain of the outer membrane lipopolysaccharides (LPSs) can play a role in the colonization of the rhizoplane by fiuorescent pseudomonads (De Weger et al, 1995). Our results show that the Oantigenic side chain of the outer membrane LPSs of strain WCS417r is involved in the bacterial colonization within the root.…”

Section: Discussionmentioning

confidence: 60%

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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: 60%

“…, u ^Ax. A., .^ (De Weger et al, 1995). Although an adequate * To whom correspondence should be addressed.…”

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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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“…Their efficacy has been related both to their antagonistic activities and to their rhizosphere competence (4,6). Overall, biological control of soilborne disease achieved by fluorescent pseudomonads is often inconsistent (15,40).…”

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confidence: 99%

Involvement of Nitrate Reductase and Pyoverdine in Competitiveness of Pseudomonas fluorescens Strain C7R12 in Soil

Mirleau

Philippot

Corberand

et al. 2001

Appl Environ Microbiol

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Involvement of nitrate reductase and pyoverdine in the competitiveness of the biocontrol strain Pseudomonas fluorescens C7R12 was determined, under gnotobiotic conditions, in two soil compartments (bulk and rhizosphere soil), with the soil being kept at two different values of matric potential (؊1 and ؊10 kPa). Three mutants affected in the synthesis of either the nitrate reductase (Nar ؊ ), the pyoverdine (Pvd ؊ ), or both (Nar ؊ Pvd ؊ ) were used. The Nar ؊ and Nar ؊ Pvd ؊ mutants were obtained by site-directed mutagenesis of the wildtype strain and of the Pvd ؊ mutant, respectively. The selective advantage given by nitrate reductase and pyoverdine to the wild-type strain was assessed by measuring the dynamic of each mutant-to-total-inoculant (wild-type strain plus mutant) ratio. All three mutants showed a lower competitiveness than the wild-type strain, indicating that both nitrate reductase and pyoverdine are involved in the fitness of P. fluorescens C7R12. The double mutant presented the lowest competitiveness. Overall, the competitive advantages given to C7R12 by nitrate reductase and pyoverdine were similar. However, the selective advantage given by nitrate reductase was more strongly expressed under conditions of lower aeration (؊1 kPa). In contrast, the selective advantage given by nitrate reductase and pyoverdine did not differ in bulk and rhizosphere soil, indicating that these bacterial traits are not specifically involved in the rhizosphere competence but rather in the saprophytic ability of C7R12 in soil environments.

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“…On a global scale, M. phaseolina and R. solani have been reported to be associated with more than 500 plant species [2]. As such, these pathogenic microorganisms are major and chronic threat to food production and ecosystem stability world wide [3]. In North East India, use of pesticide to control these diseases in broad bean is not a common practice but in the season of severe incidence, particularly under wet soil conditions, the damage of crop due to the disease may be total.…”

Section: Introductionmentioning

confidence: 99%

Screening of Rhizobacteria for Their Plant Growth Promotion Ability and Antagonism Against Damping off and Root Rot Diseases of Broad Bean (Vicia faba L.)

et al. 2011

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Development of microbial inoculants from rhizobacterial isolates with potential for plant growth promotion and root disease suppression require rigorous screening. Fifty-four (54) fluorescent pseudomonads, out of a large collection of rhizobacteria from broad bean fields of 20 different locations within Imphal valley of Manipur, were initially screened for antifungal activity against Macrophomina phaseolina and Rhizoctonia solani, of diseased roots of broad bean and also three other reference fungal pathogens of plant roots. Fifteen fluorescent pseudomonas isolates produced inhibition zone (8-29 mm) of the fungal growth in dual plate assay and IAA like substances (24.1-66.7 lg/ml) and soluble P (12.7-56.80 lg/ml) in broth culture. Among the isolates, RFP 36 caused a marked increase in seed germination, seedling biomass and control of the root borne pathogens of broad bean. PCR-RAPD analysis of these isolates along with five MTCC reference fluorescent pseudomonas strains indicated that the RFP-36 belonged to a distinct cluster and the PCR of its genomic DNA with antibiotic specific primers Phenazine-1-carboxylic acid and 2, 4-diacetyl phloroglucinol suggested possible occurrence of gene for the potent antibiotics. Overall, the result of the study indicated the potential of the isolate RFP 36 as a microbial inoculant with multiple functions for broad bean.

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Colonization of the rhizosphere of crop plants by plant-beneficial pseudomonads

Cited by 97 publications

References 24 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

Involvement of Nitrate Reductase and Pyoverdine in Competitiveness of Pseudomonas fluorescens Strain C7R12 in Soil

Screening of Rhizobacteria for Their Plant Growth Promotion Ability and Antagonism Against Damping off and Root Rot Diseases of Broad Bean (Vicia faba L.)

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