Researchers have just discovered a previously unknown process that gives meaning to the “secret decisions” that plants make when they release carbon into the atmosphere.
“We’ve found that plants control their breathing in a way we didn’t expect, they control the amount of carbon in photosynthesis they maintain to generate biomass through a metabolic channel,” said Harvey Millar, a plant biochemist at the University of Western Australia, in ScienceAlert.
“This happens just like the step before you decide to burn a compound called pyruvate to make and release CO2 into the atmosphere.”
If you think about the biology of the institute, you may remember that during photosynthesis, plants make sugar or sucrose. The plant usually makes an excess of sucrose; one part is stored, another is degraded. This is called the citric acid (or tricarboxylic acid) cycle and is equally important for life.
As part of this cycle, sucrose, which has twelve carbon atoms, breaks down into glucose with six carbons. Glucose is then broken down into pyruvate, which has three carbons. The use of pyruvate as energy produces carbon as a waste product, so it is at this point that the “decision” is made at the plant.
“Pyruvate is the last point for a decision,” Millar told ScienceAlert.
“You can burn it and release CO2, or you can use it to build phospholipids, stored vegetable oils, amino acids, and other things you need to make biomass.”
The discovery occurred while working on a classic plant model organism called thale cress (Arabidopsis thaliana). The researchers, led by plant molecular scientist at the University of Western Australia Xuyen Le, labeled pyruvate with C13 (a carbon isotope) to track where it moved during the citric acid cycle. find that pyruvate from different sources was being used differently.
This means that the plant can track the source of pyruvate and act accordingly, choosing to release it or keep it for other purposes.
“We found that a mitochondrial transporter directs pyruvate to the breath to release CO2, but otherwise produced pyruvate is conserved by plant cells to generate biomass; if the transporter is blocked, plants use pyruvate other avenues for breathing, “Le said. .
“Imported pyruvate was the preferred source for citrate production.”
This ability to make decisions, the team suggests, breaks the normal rules of biochemistry, where normally every reaction is a competition and processes do not control where the product goes.
“Metabolic channeling breaks these rules by revealing reactions that don’t behave that way, but are established decisions in metabolic processes that are protected from other reactions,” Millar says.
“This is not the first metabolic channel to be found, but they are relatively rare, and this is the first evidence of one that governs this process in respiration.”
Although plants are wonderful stores of CO2 (only forests store about 400 gigatons of carbon), not all of the CO2 molecules that plants absorb are preserved. About half of the carbon dioxide absorbed by plants is released back into the atmosphere.
Being able to get plants to store a little more carbon dioxide in this process could be a fascinating way to help our climate change issues.
“When we think about building and reproducing plants for the future, we should not only think about how good foods and foods can be for our health, but also whether they can be good carbon stores for the health of the atmosphere that we all depend on. “Millar told ScienceAlert.
This future test is yet to come, as researchers have just discovered this biochemical process. But if we can hijack the way plants make decisions about carbon storage, it could be a piece of the biggest climate change mitigation puzzle.
The research has been published in Nature Plants.