The Oxidative Paradox in Low Oxygen Stress in Plants

Reactive oxygen species (ROS) are part of aerobic environments, and variations in the availability of oxygen (O₂) in the environment can lead to altered ROS levels. In plants, the O₂ sensing machinery guides the molecular response to low O₂, regulating a subset of genes involved in metabolic adaptations to hypoxia, including proteins involved in ROS homeostasis and acclimation. In addition, nitric oxide (NO) participates in signaling events that modulate the low O₂ stress response. In this review, we summarize recent findings that highlight the roles of ROS and NO under environmentally or developmentally defined low O₂ conditions. We conclude that ROS and NO are emerging regulators during low O₂ signalling and key molecules in plant adaptation to flooding conditions.