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Abstract

Global warming is associated with an increase in flooding events that are characterized by unexpected occurrence, regimes and localization. Unusual water submersion leading to limited oxygen (O2) availability can severely affect crop production but also modify the wild plant distribution. A shift from mitochondrial respiration to fermentation is the metabolic hallmark of O2 limitation, but several morphological, physiological and biochemical adaptations have been evolved in plants to cope with O2 level variation. To generate this array of adaptive responses that finally lead to plant survival, a mechanism to sense O2  variation needs to be exploited by plants, possibly relying on a direct sensor of O2, as found in other organisms. In the Arabidopsis thaliana plant model, a direct O2 sensing mechanism has recently been discovered, setting a milestone in plant physiology. Some transcription factors (TF) of the Ethylene Responsive Factors group VII family (ERF-VII! ) have emerged as pivotal regulators of low O2 responses. Members of the ERF-VII group possess a characteristic N-terminal amino acid (N-degron) with a cysteine residue at the second position that leads to specific degradation by the N-end rule dependent proteasome pathway. It was also shown that both O2 and nitric oxide (NO) are required to destabilize the ERF-VII TFs and that a reduction in the availability of either gas is sufficient to stabilize these proteins.The finding that NO plays a critical role in the perception of O2 in plants is a major breakthrough in plant physiology and opens up new possibilities for understanding the adaptation and improve flooding tolerance in crops.