Metabolic and transcriptomic changes induced in Arabidopsis by the rhizobacterium Pseudomonas fluorescens SS101.
Systemic resistance induced in plants by nonpathogenic rhizobacteria is typically effective against multiple pathogens. Here, we show that root-colonizing Pseudomonas fluorescens strain SS101 (Pf.SS101) enhanced resistance in Arabidopsis (Arabidopsis thaliana) against several bacterial pathogens, including Pseudomonas syringae pv tomato (Pst) and the insect pest Spodoptera exigua. Transcriptomic analysis and bioassays with specific Arabidopsis mutants revealed that, unlike many other rhizobacteria, the Pf.SS101-induced resistance response to Pst is dependent on salicylic acid signaling and not on jasmonic acid and ethylene signaling. Genome-wide transcriptomic and untargeted metabolomic analyses showed that in roots and leaves of Arabidopsis plants treated with Pf.SS101, approximately 1,910 genes and 50 metabolites were differentially regulated relative to untreated plants. Integration of both sets of "omics" data pointed to a prominent role of camalexin and glucosinolates in the Pf.SS101-induced resistance response. Subsequent bioassays with seven Arabidopsis mutants (myb51, cyp79B2cyp79B3, cyp81F2, pen2, cyp71A12, cyp71A13, and myb28myb29) disrupted in the biosynthesis pathways for these plant secondary metabolites showed that camalexin and glucosinolates are indeed required for the induction of Pst resistance by Pf.SS101. Also for the insect S. exigua, the indolic glucosinolates appeared to play a role in the Pf.SS101-induced resistance response. This study provides, to our knowledge for the first time, insight into the substantial biochemical and temporal transcriptional changes in Arabidopsis associated with the salicylic acid-dependent resistance response induced by specific rhizobacteria.
Laboratory of Phytopathology , 6708 PB Wageningen, The Netherlands.
Judith E
JE
van de Mortel
Ric C H
RC
de Vos
Ester
E
Dekkers
Ana
A
Pineda
Leandre
L
Guillod
Klaas
K
Bouwmeester
Joop J A
JJ
van Loon
Marcel
M
Dicke
Jos M
JM
Raaijmakers
D000818:Animals; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology* / Q000469:parasitology; D029681:Arabidopsis Proteins / Q000378:metabolism; D002853:Chromatography, Liquid; D060467:Disease Resistance / Q000235:genetics / Q000276:immunology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant / Q000235:genetics; D005961:Glucosinolates / Q000378:metabolism; D060434:Herbivory / Q000235:genetics; D007211:Indoles / Q000378:metabolism; D013058:Mass Spectrometry; D053858:Metabolic Networks and Pathways / Q000235:genetics; D055442:Metabolome / Q000235:genetics*; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D011551:Pseudomonas fluorescens / Q000502:physiology*; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D018411:Spodoptera / Q000502:physiology; D013844:Thiazoles / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics*; D000094162:Phytoalexins
D029681:Arabidopsis Proteins; D005961:Glucosinolates; D007211:Indoles; D020156:Salicylic Acid; D013844:Thiazoles; C105496:NPR1 protein, Arabidopsis; C102405:camalexin; D000094162:Phytoalexins