A new link between the “power stations” of plants
Mitochondria were found to draw oxygen from chloroplasts, modifying photosynthesis and stress responses.
A new study from the University of Helsinki reveals how plant mitochondria draw molecular oxygen away from chloroplasts, an interaction not previously documented. The discovery sheds new light on how plants regulate oxygen inside their tissues, with implications for understanding plant metabolism and stress acclimation.
The research, led by
Dr. Alexey Shapiguzov (PhD, Docent) from the University’s
Centre of Excellence in Tree Biology on the Viikki campus, has been published in
Plant Physiology.
Oxygen as a central factor in plant life
Oxygen gas is central to plant metabolism, growth, stress acclimation and immunity. Recent research at the University of Helsinki has shown that
oxygen triggers wound healing in plants. Yet, despite its importance, scientists still lack understanding of how oxygen levels inside plant tissues are controlled.
In plant cells, oxygen dynamics are dominated by two organelles:
mitochondria that consume oxygen during respiration, and
chloroplasts that produce oxygen as a by‑product of photosynthesis.
While both cellular respiration and photosynthesis are well studied, the exchange of oxygen between mitochondria and chloroplasts remains largely unexplored.
Genetically modified Arabidopsis enables the study of mitochondrial functions
To investigate this gap, the research team examined genetically modified lines of the model plant
Arabidopsis thaliana that carry mitochondrial defects. These defects switch on alternative respiratory enzymes, boosting mitochondrial oxygen consumption.
Genetically modified lines were found to carry two key features:
- Increased mitochondrial respiration lowered oxygen levels in tissues.
- Chloroplasts in these plants became resistant to methyl viologen, a chemical that diverts electrons from photosystem I to oxygen, producing reactive oxygen species.
Under low‑oxygen conditions achieved by exposing the plants to nitrogen gas, the electron transfer to oxygen dropped dramatically. This indicated that methyl viologen was simply running out of its required substrate: oxygen.
Mitochondria “suck out” oxygen from chloroplasts
The results suggest a previously undocumented interaction: when stressed, mitochondria can reduce oxygen levels inside chloroplasts by consuming more of it. This “oxygen drain” affects photosynthesis and metabolism of reactive oxygen species, which can help plants adjust to environmental changes.
According to Dr. Shapiguzov, to our knowledge, this is the first evidence that mitochondria influence chloroplasts through intracellular oxygen exchange. It adds a new layer to our understanding of how plants regulate energy metabolism and cope with stress.
New insights regarding plant resilience
By understanding how respiration and photosynthesis interact through oxygen exchange, scientists can better understand plant energy metabolism and responses to environmental changes such as day‑night transitions or flooding. This can help develop new crop varieties.
The discovered interaction also provides new ways of measuring and imaging plant physiology, which can be helpful in breeding and in early stress detection.
Research article in Plant Physiology.