Photosynthesis is the process used by plants to transform water, sunlight, and carbon dioxide into oxygen and energy in the form of sugar. But a plant doesn’t grow as fast as the carbon it takes in by photosynthesis because it releases most of its carbon as CO2 in plant respiration.
This prevents plants from being the best carbon sinks, limiting how much they can assist reduce CO2 levels in the atmosphere. A carbon sink is anything that absorbs more carbon from the atmosphere than it releases.
According to a new study from The University of Western Australia– plants make their secret decisions about how much carbon to release back into the atmosphere via a previously unknown process. Plants keep this secret locked away within mitochondria, where CO2 release occurs.
Professor Harvey Millar from UWA’s School of Molecular Sciences said, “Our research, led by the Ph.D. candidate and Forrest Scholar Xuyen Le, discovered this CO2 release decision is governed by a previously unknown process, a metabolic channel that directs a product of sugar called pyruvate to be oxidized to CO2 or kept to make plant biomass.”
Ms. Le said, “We found that a transporter on mitochondria directs pyruvate to respiration to release CO2, but pyruvate made in other ways is kept by plant cells to build biomass – if the transporter is blocked, plants then use pyruvate from other pathways for respiration.”
Professor Millar said, “the research shows that plants can differentiate and choose one pyruvate source over another for CO2 release. This secret process breaks the normal rules of biochemistry, where the next step in a process does not know the origin of the product from the step before.”
“Understanding the plant’s respiration secret to use a metabolic channel to prioritize carbon release over keeping it to make biomass provides a new opportunity to influence the decision at the last moment.”
“This could be done by limiting this channeling to respiration or making new channels to direct carbon inside mitochondria back towards biomass production, limiting CO2 release from plants.”
“It shows that current discussions around carbon net-zero and the role that crops, forests, and grasslands can play should also include conversations on what happens inside plants, alongside global financial decisions.”
- Le, X.H., Lee, C.P., Monachello, D. et al. Metabolic evidence for distinct pyruvate pools inside plant mitochondria. Nat. Plants (2022). DOI: 10.1038/s41477-022-01165-3