Simultaneous Interaction of Arabidopsis thaliana with Bradyrhizobium Sp. Strain ORS278 and Pseudomonas syringae pv. tomato DC3000 Leads to Complex Transcriptome Changes

Abstract

Induced systemic resistance (ISR) is a process elicited by telluric microbes, referred to as plant growth-promoting rhizobacteria (PGPR), that protect the host plant against pathogen attacks. ISR has been defined from studies using Pseudomonas strains as the biocontrol agent. Here, we show for the first time that a photosynthetic Bradyrhizobium sp. strain, ORS278, also exhibits the ability to promote ISR in Arabidopsis thaliana, indicating that the ISR effect may be a widespread ability. To investigate the molecular bases of this response, we performed a transcriptome analysis designed to reveal the changes in gene expression induced by the PGPR, the pathogen alone, or by both. The results confirm the priming pattern of ISR described previously, meaning that a set of genes, of which the majority was predicted to be influenced by jasmonic acid or ethylene, was induced upon pathogen attack when plants were previously colonized by PGPR. The analysis and interpretation of transcriptome data revealed that 12-oxo-phytodienoic acid, an intermediate of the jasmonic acid biosynthesis pathway, is likely to be an actor in the signaling cascade involved in ISR. In addition, we show that the PGPR counterbalanced the pathogen-induced changes in expression of a series of genes.

Jasmonate signaling in plant interactions with resistance-inducing beneficial microbes

“…strain ORS278 (Cartieaux et al, 2008). These studies uncovered a large number of JA/ET-regulated genes that showed a primed expression pattern after pathogen infection.…”

Metabolic and Transcriptomic Changes Induced in Arabidopsis by the Rhizobacterium Pseudomonas fluorescens SS101

“…Furthermore, for only few rhizobacterial strains, transcriptomic analyses have been conducted to unravel the molecular changes in plants associated with induced systemic resistance (Cartieaux et al, 2003(Cartieaux et al, , 2008Verhagen et al, 2004;Wang et al, 2005;Weston et al, 2012). Almost all of these microarray studies revealed relatively few transcriptional changes: for instance, plant-growth promoting Pseudomonas thivervalensis strain MLG45 induced transcriptional changes in 63 genes in the shoots and in nine genes in the roots of Arabidopsis (Arabidopsis thaliana), with an increase in defense-related transcripts and a repression of photosynthesis-related genes (Cartieaux et al, 2003).…”

Pseudomonas fluorescens WCS374r-Induced Systemic Resistance in Rice against Magnaporthe oryzae Is Based on Pseudobactin-Mediated Priming for a Salicylic Acid-Repressible Multifaceted Defense Response

“…However, downstream of NPR1, the ISR and SAR signaling pathways diverge because, unlike SAR, ISR is not accompanied by the concomitant activation of PR genes (Pieterse et al, 1996;VanWees et al, 1997VanWees et al, , 1999. Instead, ISR-expressing plants are primed for enhanced expression of predominantly JA-and ETregulated genes upon pathogen infection (Verhagen et al, 2004;Cartieaux et al, 2008).…”