MAPK-targeted VQ-proteins: Novel modulators of plant immune responses
M. WEYHE (1), P. Pecher (2), L. Eschen-Lippold (1), D. Scheel (3), J. Lee (1) (1) Leibniz Institute of Plant Biochemistry, Germany; (2) John Innes Centre, United Kingdom; (3) Leibniz Institute of Plant Biochemistry, Germany

One of the first layers of plant immunity relies on the sensing of conserved pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors at the cell surface. This triggers complex cellular signal transduction networks including activation of mitogen-activated protein kinases (MAPKs; e.g. MPK3 and MPK6). Phosphorylation of MPK3/6 substrates eventually leads to the appropriate responses via, for example, transcriptional reprogramming of defence-related genes. We identified a subset of 10 Arabidopsis thaliana VQ-motif containing proteins (VQPs) to be novel substrates of MPK3 and MPK6 and designated them as MPK3/6-targeted VQP1-10 (MVQ1-10). VQPs constitute a plant-specific protein family hallmarked by a conserved F(R/K)xxVQxLTG sequence motif. All MVQs (except MVQ8) interacted with WRKY transcription factors from the subgroup I and IIc in a yeast-two-hybrid assay, in a VQ-motif-dependent manner, suggesting a role in control of transcription. Along this notion, analysis of promoter activity of a defence gene reporter revealed, that MVQ1 could negatively regulate PAMP-induced gene expression. Thus, MVQs add a new layer of transcriptional control functions to WRKYs, which are well-known for their roles in stress responses. We postulate the existence of a protein-protein interaction network of VQP-WRKY combinatorial possibilities and their function to modulate plant immune responses can be further fine-tuned through post-translational modification of MVQs by PAMP-activated MAPKs.

Abstract Number: P18-693
Session Type: Poster