Salicylic Acid Suppresses Jasmonic Acid Signaling Downstream of SCFCOI1-JAZ by Targeting GCC Promoter Motifs via Transcription Factor ORA59    

Abstract

Antagonism between the defense hormones salicylic acid (SA) and jasmonic acid (JA) plays a central role in the modulation of the plant immune signaling network, but the molecular mechanisms underlying this phenomenon are largely unknown. Here, we demonstrate that suppression of the JA pathway by SA functions downstream of the E3 ubiquitin-ligase Skip-Cullin-F-box complex SCF COI1 , which targets JASMONATE ZIM-domain transcriptional repressor proteins (JAZs) for proteasomemediated degradation. In addition, neither the stability nor the JA-induced degradation of JAZs was affected by SA. In silico promoter analysis of the SA/JA crosstalk transcriptome revealed that the 1-kb promoter regions of JA-responsive genes that are suppressed by SA are significantly enriched in the JA-responsive GCC-box motifs. Using GCC:GUS lines carrying four copies of the GCC-box fused to the b-glucuronidase reporter gene, we showed that the GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Using plants overexpressing the GCC-box binding APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factors ERF1 or ORA59, we found that SA strongly reduces the accumulation of ORA59 but not that of ERF1. Collectively, these data indicate that the SA pathway inhibits JA signaling downstream of the SCF COI1 -JAZ complex by targeting GCC-box motifs in JA-responsive promoters via a negative effect on the transcriptional activator ORA59.

Arabidopsis MYC Transcription Factors Are the Target of Hormonal Salicylic Acid/Jasmonic Acid Cross Talk in Response to Pieris brassicae Egg Extract

“…VSP2 expression was still inhibited by a combined egg extract and wound treatment in the quadruple bhlh3 bhlh13 bhlh14 bhlh17 mutant, ruling out the involvement of this family of repressors in egginduced SA/JA cross talk. It would be interesting to test their role in the ERF branch of the JA pathway, but altogether our data and those of Van der Does et al (2013) point to separate mechanisms to modulate JAdependent transcriptional responses. On one hand, stabilized JAZs and bHLH repressors counteract the activation of JA responses to fine-tune defense and development.…”

“…Additional experiments demonstrated that ET can override NPR1 dependency of SA-JA antagonism, indicating that biotic induction of ET modulates the interaction between SA and JA pathways (Leon-Reyes et al, 2010b). Two recent studies discovered that SA treatment promotes ORA59 protein degradation (Van der Does et al, 2013) and inhibit ORA59 expression (Zander et al, 2014), providing the first clues on how gene expression from the ERF branch of the JA pathway is suppressed.…”

Arabidopsis PECTIN METHYLESTERASEs Contribute to Immunity against Pseudomonas syringae

“…Pma ES4326 induces robust accumulation of SA, whereas A. brassicicola does not (De Vos et al, 2005;Wang et al, 2008). SA inhibits JA signaling by targeting GCC promoter elements in the ERF-dependent branch of JA signaling (Van der Does et al, 2013). Consistently, Pma ES4326 induces expression of the SA reporter gene PATHOGENESIS-RELATED1, the JA/ABA reporter gene VEGETATIVE STORAGE PROTEIN2, but not the JA/ET reporter gene PLANT DEFENSIN 1.2 (PDF1.2) (Wang et al, 2008).…”

“…ERF-type transcription factors have not been shown to interact with JAZ repressors. SA suppresses JA signaling downstream of the ET-dependent signaling branch in an ORA59-dependent manner (Van der Does et al, 2013).…”

Methyl jasmonate and its potential in cancer therapy

“…1,2 In a sense of being widely accepted, pathogens with a biotrophic lifestyle are particularly sensitive to salicylic acid (SA) -mediated defenses, whereas necrotrophic pathogens and herbivorous insects are resisted through jasmonate, or its derivatives, -mediated defenses. 3 Although molecular mechanisms of MeJa action, as well as the antagonistic effects of MeJa and other defense hormones such as SA, on the modulation of plant immune signaling networks have been extensively studied, 3 the dynamic cellular events and signaling cascade profiles following the introduction of MeJa in a single living cell are largely unknown.…”