The N-degron pathways are a set of degradation pathways that target proteins for ubiquitin-mediated proteolysis based on the identify of their N-terminus. In plants, the PROTEOLYSIS6 (PRT6) N-degron pathway has emerged as a key regulator of diverse plant processes1. In particular, it coordinates development and stress-responses through the oxygen-dependent control of several substrates1, including transcription factors (ERFVIIs2,3, ZPR24) and the polycomb protein VRN25.
VRN2 is a homolog of animal Suz12, a core subunit of the conserved polycomb repressive complex 2 (PRC2) that catalyses the tri-methylation of histones (H3K27me3) to epigenetically silence gene expression. Our work to date suggests that post-translational control of VRN2 abundance allows it to function as a plant-specific “sensor subunit” that connects a subset of PRC2 activities to the perception of environmental and positional cues5,6. Supporting this hypothesis, we have now shown that VRN2 directly couples signals from the environment to the epigenetic control of development and plays a key role in establishing longer term flooding stress “memory”. We have also identified a second histone modifying protein - an H3K27 demethylase, which counterbalances PRC2 activity - that is recruited to gene targets in an ERFVII-dependent manner. Taken together, our work suggests that the PRT6 N-degron pathway influences histone methylation dynamics in response to oxygen availability to coordinate plant growth and environmental stress adaptation through controlling the stability and recruitment of antagonistic histone modifiers.