Plants' Homeostatic Reponse to Hypoxia

Plants and animals are aerobes, and therefore require in order to to respire and for energy production. This article explains how the plant response to hypoxia (decline in oxygen availability) is a bit different from the animal response to hypoxia. The decline in oxygen triggers a change in gene transcription and messenger RNA that promote anaerobic metabolism, ergo sustaining substrate-level ATP production. Furthermore, oxygen sensing has not been ascribed to a mechanism of gene regulation in response to oxygen deprivation, like it is in animals. In studying Arabidopsis, researchers showed that the N-end rule pathway of targeted proteolysis acted as a homeostatic sensor of severe low oxygen levels in the plant, through its regulation of key hypoxia-response transcription factors. Researches also found that plants lacking components of the N-end rule pathway expressed core hypoxia-response genes and were more tolerant of hypoxic stress. Hypoxia-associated ethylene response factor group VII transcription factors of Arabidopsis were identified as substrates of this pathway. Enhanced stability of one of the proteins, HRE2, under low oxygen conditions improved hypoxia survival. It also revealed a molecular mechanism for oxygen sensing in plants by the evolutionarily conserved N-end rule pathway.