Energy and sugar signaling during hypoxia.

The major consequence of hypoxia is a dramatic reduction in energy production. At the onset of hypoxia, both oxygen and ATP availability decrease. Oxygen and energy sensing therefore converge to induce an adaptive response at both the transcriptional and translational levels. Oxygen sensing results in stabilization of the transcription factors that activate hypoxia-response genes, including enzymes required for efficient sugar metabolism, allowing plants to produce enough energy to ensure survival. The translation of the resulting mRNAs is mediated by SnRK1, acting as an energy sensor. However, as soon as the sugar availability decreases, a homeostatic mechanism, detecting sugar starvation, dampens the hypoxia-dependent transcription to reduce energy consumption and preserves carbon reserves for regrowth when oxygen availability is restored.