P-359 - Control of Arabidopsis immune and developmental gene expression through phosphorylation of VQ-motif containing transcriptional co-regulators.

Mitogen-activated protein kinases (MAPKs) are highly conserved in all eukaryotes and control cellular responses through phosphorylation of target proteins, which are often transcriptional regulators. Our interest in MAPKs relevant for plant immunity led us to analyse a subclass of VQ-motif containing proteins (VQPs) that we termed MVQs (for MAPK-targeted VQPs). MVQs bind specific WRKY transcription factors to modulate their functions. Here, selected examples from our studies on MAPK-MVQ-WRKY network during immunity and plant development will be shown. Since the motif for WRKY interaction overlaps with WRKY-DNA binding domains, it has been speculated that DNA association might be affected. Here, we will present results that support our working model that MVQs act as transcriptional co-regulators while bound to cis elements of target genes. Signalling specificities and repertoire can thus be determined by the combinatorial WRKY-VQP variations. Besides phosphorylation-mediated effects, we will also highlight examples where gene regulation may be controlled by formation of biomolecular condensates in the nucleus.