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 (O(2)) in the environment can lead to altered ROS levels. In plants, the O(2) sensing machinery guides the molecular response to low O(2), 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 O(2) stress response. In this review, we summarize recent findings that highlight the roles of ROS and NO under environmentally or developmentally defined low O(2) conditions. We conclude that ROS and NO are emerging regulators during low O(2) signalling and key molecules in plant adaptation to flooding conditions.