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Genome‐wide analysis of bacterial determinants of plant growth promotion and induced systemic resistance by Pseudomonas fluorescens
Author(s) -
Cheng Xu,
Etalo Desalegn W.,
van de Mortel Judith E.,
Dekkers Ester,
Nguyen Linh,
Medema Marnix H.,
Raaijmakers Jos M.
Publication year - 2017
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.13927
Subject(s) - biology , pseudomonas syringae , complementation , transposon mutagenesis , pseudomonas fluorescens , arabidopsis thaliana , arabidopsis , auxin , mutant , siderophore , dehydratase , genetics , auxotrophy , pseudomonas , gene , microbiology and biotechnology , transposable element , bacteria
Summary Pseudomonas fluorescens strain SS101 ( Pf .SS101) promotes growth of Arabidopsis thaliana , enhances greening and lateral root formation, and induces systemic resistance (ISR) against the bacterial pathogen Pseudomonas syringae pv. tomato ( Pst ). Here, targeted and untargeted approaches were adopted to identify bacterial determinants and underlying mechanisms involved in plant growth promotion and ISR by Pf .SS101. Based on targeted analyses, no evidence was found for volatiles, lipopeptides and siderophores in plant growth promotion by Pf .SS101. Untargeted, genome‐wide analyses of 7488 random transposon mutants of Pf .SS101 led to the identification of 21 mutants defective in both plant growth promotion and ISR. Many of these mutants, however, were auxotrophic and impaired in root colonization. Genetic analysis of three mutants followed by site‐directed mutagenesis, genetic complementation and plant bioassays revealed the involvement of the phosphogluconate dehydratase gene edd , the response regulator gene colR and the adenylsulfate reductase gene cysH in both plant growth promotion and ISR. Subsequent comparative plant transcriptomics analyses strongly suggest that modulation of sulfur assimilation, auxin biosynthesis and transport, steroid biosynthesis and carbohydrate metabolism in Arabidopsis are key mechanisms linked to growth promotion and ISR by Pf .SS101.