Evolution of response to hypoxia in the plant kingdom

In flowering plants, the transcriptional response to hypoxia is mediated by the group VII Ethylene Response Factors (ERFVIIs), whose proteolysis is oxygen-dependent via the N-degron pathway. How plants in other divisions respond to hypoxia remained largely unexplored. We combined transcriptome surveys, sequence analyses and cross-kingdom complementation to investigate the conservation and divergence of gene regulation in hypoxia in land plants. Our results suggest that ERFVII acquired oxygen-dependent destabilisation to regulate adaptive genes in the last common ancestor of vascular plants. Proteins from other ERF groups have been recruited multiple times as substrates of the N-degron pathway, although they do not seem to participate to low oxygen signalling. Finally, we identified glycolysis and fermentation genes as part of a conserved response to hypoxia across all land plant divisions. Most of these genes are ERFVII-dependent in vascular plants, although a different signalling mechanism is responsible for their activation in bryophytes.