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

Abstract

Arabidopsis (Arabidopsis thaliana) plants recognize insect eggs and activate the salicylic acid (SA) pathway. As a consequence, expression of defense genes regulated by the jasmonic acid (JA) pathway is suppressed and larval performance is enhanced. Cross talk between defense signaling pathways is common in plant-pathogen interactions, but the molecular mechanism mediating this phenomenon is poorly understood. Here, we demonstrate that egg-induced SA/JA antagonism works independently of the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor ORA59, which controls the ERF branch of the JA pathway. In addition, treatment with egg extract did not enhance expression or stability of JASMONATE ZIM-domain transcriptional repressors, and SA/JA cross talk did not involve JASMONATE ASSOCIATED MYC2-LIKEs, which are negative regulators of the JA pathway. Investigating the stability of MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that additively control jasmonate-related defense responses, we found that egg extract treatment strongly diminished MYC protein levels in an SA-dependent manner. Furthermore, we identified WRKY75 as a novel and essential factor controlling SA/JA cross talk. These data indicate that insect eggs target the MYC branch of the JA pathway and uncover an unexpected modulation of SA/JA antagonism depending on the biological context in which the SA pathway is activated.

Stress Marker Signatures in Lesion Mimic Single and Double Mutants Identify a Crucial Leaf Age-Dependent Salicylic Acid Related Defense Signal

“…High expression of PLA2A correlates with cell death, and transgenic overexpression of PLA2A enhances cell death [52,53]. WRKY75 controls crosstalk between SA/JA and ROS signals, all of which are required to activate defense regulation [54,55]. The GLTP gene in Arabidopsis has not been characterized.…”

Redox Control of Aphid Resistance through Altered Cell Wall Composition and Nutritional Quality

“…Furthermore, a transcript with homology to the Arabidopsis MYC2 transcription factor was increased significantly only in the TAO plants. Along with MYC3 and MYC4, MYC2 is a target for JAZ repressors and plays a key role in orchestrating salicylic acid (SA)/jasmonic acid (JA) cross talk in response to the perception of insect attack (Schmiesing et al, 2016). A transcript with homology to WRKY40 also was highly expressed in TAO leaves in Figure 3.…”

Citrus leprosis virus C Infection Results in Hypersensitive-Like Response, Suppression of the JA/ET Plant Defense Pathway and Promotion of the Colonization of Its Mite Vector

“…In contact with plants, some insect eggs induce high level of SA, leading to a strong reduction of the JA-mediated defenses and, hence, decreasing their interference on the future larva feeding (Little et al, 2007; Bruessow et al, 2010; Gouhier-Darimont et al, 2013; Hilfiker et al, 2014). Extracts from these eggs reduce the MYC protein levels in a SA-dependent manner (Schmiesing et al, 2016). Moreover, insects and mites secrete proteins in their saliva which modulate, and even suppress, the plant defense response (Kant et al, 2015; Villarroel et al, 2016).…”