Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 507521
Title Plant growth promotion by Pseudomonas fluorescens : mechanisms, genes and regulation
Author(s) Cheng, X.
Source Wageningen University. Promotor(en): Francine Govers; J.M. Raaijmakers, co-promotor(en): M. van der Voort. - Wageningen : Wageningen University - ISBN 9789462578753 - 192
Department(s) Laboratory of Phytopathology
EPS
Publication type Dissertation, internally prepared
Publication year 2016
Keyword(s) soil bacteria - pseudomonas fluorescens - plants - growth stimulators - soil suppressiveness - plant diseases - induced resistance - biochemistry - biosynthesis - plant-microbe interactions - transcriptomics - bodembacteriën - pseudomonas fluorescens - planten - groeistimulatoren - bodemweerbaarheid - plantenziekten - geïnduceerde resistentie - biochemie - biosynthese - plant-microbe interacties - transcriptomica
Categories Microbe-Plant Relations
Abstract

Pseudomonas fluorescens is a Gram-negative rod shaped bacterium that has a versatile metabolism and is widely spread in soil and water. P. fluorescens strain SBW25 (Pf.SBW25) is a well-known model strain to study bacterial evolution, plant colonization and biocontrol of plant diseases. It produces the biosurfactant viscosin, a lipopeptide that plays a key role in motility, biofilm formation and activity against zoospores of Phytophthora infestans and other oomycete pathogens. In addition to viscosin, Pf.SBW25 produces other metabolites with activity against plant pathogens. The production of these yet unknown metabolites appeared to be regulated by the GacS/GacA two-component regulatory system (the Gac-system). The second P. fluorescens strain SS101 (Pf.SS101) studied in this thesis is known for its plant growth-promoting activities but the underlying mechanisms and genes are largely unknown. Therefore, in this study, we aimed to identify novel metabolites and biosynthetic genes in Pf.SBW25 and Pf.SS101, and to investigate their role in plant growth promotion and biocontrol. To this end, a multidisciplinary approach involving bioinformatic analysis of the genome sequences of strains Pf.SBW25 and Pf.SS101, microarray-based expression profiling, screening of genomic libraries, bioactivity assays, mass spectrometric image analysis (MALDI-IMS) and GC/MSMS analysis was adopted. In conclusion, we showed that the GacS/GacA two-component system as a global regulator of the expression of genes play important roles in antagonism of Pseudomonas fluorescens toward plant pathogenic microbes as well as in plant growth promotion and ISR. Growth promotion by P. fluorescens is associated with alterations in auxin biosynthesis and transport, steroid biosynthesis, carbohydrate metabolism and sulfur assimilation. Moreover, advanced chemical profiling allowed us to compare the metabolite profiles of free-living P. fluorescens and P. fluorescens living in association with plant roots. A better understanding of yet unknown mechanisms exploited by the various Pseudomonas fluorescens strains will lead to new opportunities for the discovery and application of natural bioactive compounds for both industrial and agricultural purposes.

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