Transcription factors WRKY70 and WRKY11 served as regulators in rhizobacteriumBacillus cereusAR156-induced systemic resistance toPseudomonas syringaepv.tomatoDC3000 in Arabidopsis

Abstract

The activation of both the SA and JA/ETsignalling pathways may lead to more efficient general and broad resistance to Pst DC3000 by non-pathogenic rhizobacteria. However, the mechanisms that govern this simultaneous activation are unclear. Using Arabidopsis as a model system, two transcription factors, WRKY11 and WRKY70, were identified as important regulators involved in Induced Systemic Resistance (ISR) triggered by Bacillus cereus AR156. The results revealed that AR156 treatment significantly stimulated the transcription of WRKY70, but suppressed that of WRKY11 in Arabidopsis leaves. Furthermore, they were shown to be required for AR156 enhancing the activation of cellular defence responses and the transcription level of the plant defence response gene. Overexpression of the two transcription factors in Arabidopsis also showed that they were essential for AR156 to elicit ISR. AR156-triggered ISR was completely abolished in the double mutant of the two transcription factors, but still partially retained in the single mutants, indicating that the regulation of the two transcription factors depend on two different pathways. The target genes of the two transcription factors and epistasis analysis suggested that WRKY11 regulated AR156-triggered ISR through activating the JA signalling pathway, and WRKY70 regulated the ISR through activating the SA signalling pathway. In addition, both WRKY11 and WRKY70 modulated AR156-triggered ISR in a NPR1-dependent manner. In conclusion, WRKY11 and WRKY70 played an important role in regulating the signalling transduction pathways involved in AR156-triggered ISR. This study is the first to illustrate the mechanism by which a single rhizobacterium elicits ISR by simultaneously activating both the SA and JA/ET signalling pathways.

Biological control of Pythium, Rhizoctonia and Sclerotinia in lettuce: association of the plant protective activity of the bacterium Paenibacillus alvei K165 with the induction of systemic resistance

“…Indeed, the study of Guo & Stotz (2007) has also concluded that defence against S. sclerotiorum in Arabidopsis is dependent on SA and ET/ JA signalling. According to Jiang et al (2016), the simultaneous activation of the SA-and ET/JA-signalling pathways is modulated via WRKY11 and WRKY70 and leads to an additive effect on the level of induced protection. It is tempting to speculate that the highly protective activity of K165 against S. sclerotiorum probably lies in the additive effect of the simultaneous activation of the SA-and ET/JA-dependent defences.…”

Biological control of septoria leaf blotch and growth promotion in wheat by Paenibacillus sp. strain B2 and Curtobacterium plantarum strain EDS

“…PGPR-mediated induced systemic resistance (ISR) has been demonstrated against fungi, bacteria, and viruses in Arabidopsis (Arabidopsis thaliana), bean (Phaseolus vulgaris), and tomato (Solanum lycopersicum) under conditions in which the inducing bacteria and the challenging pathogens remained spatially separated . ISR induced by PGPR is phenotypically similar to pathogen-induced systemic acquired resistance (SAR) (Jiang et al, 2015;Van der Ent et al, 2008;Van Loon et al, 1998). Whereas SAR depends on the salicylic acid (SA) pathway, which is followed by pathogenesis-related (PR) gene expression, such as PR1, PR2, and PR5 (Jiang et al, 2016(Jiang et al, , 2015, ISR depends both on the jasmonic acid (JA), and ethylene (ET) pathways (Jiang et al, 2015;Van Loon et al, 1998) and is combined with the accumulation of phytoalexins and formation of physical barriers such as callose and lignin (Jiang et al, 2015;Van Oosten et al, 2008).…”

Characterization of Rhodopseudomonas palustris population dynamics on tobacco phyllosphere and induction of plant resistance to Tobacco mosaic virus

“…Such type of ISR was also documented in Arabidopsis thaliana triggered by the plant growth‐promoting rhizobacterium Bacillus cereus AR156 (Niu et al ., ). In AR156‐triggered ISR, the activating JA‐signalling pathway was achieved by downregulating the transcription factor WRKY11 and activating SA‐signalling pathway by upregulating WRKY70 (Jiang et al ., ). Based on our findings, it can be speculated that GJ‐22 may produce unique microbe‐associated molecular patterns (MAMPs) recognized by N. benthamiana, leading to the generation of this distinct ISR.…”