Low oxygen response mechanisms in green organisms

Area of Science:

• Plant and algal biology
• Molecular responses to environmental stress

Background:

• Low oxygen stress is a common environmental challenge for green organisms.
• Organisms respond to hypoxia by shifting metabolism from respiration to fermentation.
• Plants and algae employ molecular mechanisms to sense and adapt to low oxygen conditions.

Purpose of the Study:

• To review recent findings on molecular mechanisms of low oxygen sensing and response in plants and algae.
• To highlight the role of ethylene responsive factors (ERFs) in hypoxia adaptation.
• To explore evolutionary divergence in hypoxia response pathways between higher plants and microalgae.

Main Methods:

• Review of current scientific literature on plant and algal responses to hypoxia.
• Analysis of molecular mechanisms, including oxygen sensing by ethylene responsive factors (ERFs).
• Comparative study of hypoxia adaptation strategies in *Arabidopsis thaliana*, *Oryza sativa*, and *Chlamydomonas reinhardtii*.

Main Results:

• A direct oxygen sensing system involving ERFs has been identified in *Arabidopsis thaliana*.
• ERFs mediate physiological and anatomical changes in response to hypoxia in *Oryza sativa*, with genotypic variations.
• Hypoxia response in *Chlamydomonas reinhardtii* suggests independent evolutionary pathways compared to higher plants.

Conclusions:

• Ethylene responsive factors (ERFs) are critical regulators of hypoxia responses across diverse green organisms.
• Understanding ERF-mediated oxygen sensing provides insights into metabolic reprogramming under low oxygen stress.
• Further research is needed to elucidate the independent evolution of fermentative metabolism modulation in microalgae.