Apart from playing a key role in important biochemical reactions, molecular oxygen (O₂) and its by-products also have crucial signaling roles in shaping plant developmental programs and environmental responses. Even under normal conditions, sharp O₂ gradients can occur within the plant when cellular O₂ demand exceeds supply, especially in dense organs such as tubers, seeds and fruits. Spatial and temporal variations in O₂ concentrations are important cues for plants to modulate development (van Dongen & Licausi, 2015; Considine et al., 2016). Environmental conditions can also expand the low O₂ regions within the plant. For example, excessive rainfall can lead to partial or complete plant submergence resulting in O₂ deficiency in the root or the entire plant (Voesenek & Bailey-Serres, 2015). Climate change associated increases in precipitation events have made flooding a major abiotic stress threatening crop production and food sustainability. This increased flooding and associated crop losses highlight the urgency of understanding plant flooding responses and tolerance mechanisms.