Researchers at the University of Helsinki have found that mitochondria in plant cells can draw oxygen away from chloroplasts, revealing a new interaction that affects photosynthesis and stress responses. This discovery, published in Plant Physiology, explains how plants manage internal oxygen levels. The study used genetically modified Arabidopsis thaliana plants to observe these processes.
A team led by Dr. Alexey Shapiguzov at the University of Helsinki's Centre of Excellence in Tree Biology has identified a previously unknown mechanism in plant cells. Mitochondria, which produce energy through respiration, can actively reduce oxygen levels around chloroplasts, the sites of photosynthesis. This oxygen exchange alters how plants handle reactive oxygen species and adapt to environmental stresses.
The research focused on Arabidopsis thaliana, a model plant, with versions genetically modified to have mitochondrial defects that activate alternative respiratory enzymes. These modifications increased oxygen consumption by mitochondria, leading to lower oxygen in plant tissues. As a result, chloroplasts showed resistance to methyl viologen, a chemical that typically generates reactive oxygen species by diverting electrons to oxygen.
Experiments under low-oxygen conditions, created by exposing plants to nitrogen gas, further confirmed the interaction. Electron transfer to oxygen decreased sharply, indicating insufficient oxygen availability for the chemical's action. Dr. Shapiguzov stated, "to our knowledge, this is the first evidence that mitochondria influence chloroplasts through intracellular oxygen exchange."
Oxygen plays a key role in plant metabolism, growth, immune responses, and stress adaptation, including wound healing. While photosynthesis releases oxygen and respiration consumes it, the direct influence between these organelles was not previously understood. This finding could enhance predictions of plant responses to changes like day-night cycles or flooding.
The discovery may improve tools for measuring plant physiology, aiding early stress detection in crops and supporting breeding efforts. The study was published in Plant Physiology in 2026.
