Researchers uncover potential climate change-nutrition connection in plant metabolism

Michigan State University researchers uncover potential climate change-nutrition links in plant metabolism

Michigan State University researchers may have discovered a link between climate change and plant nutrition. Credit: Hermann Schachner via Wikimedia Commons (plant cell) / Mike Erskine via Unsplash (arid land)

A new study from researchers at Michigan State University underscores that we still need to learn about how plants will function—and how nutritious they will be—as more carbon enters our atmosphere.

That same carbon input helps drive climate change, suggests this new work, published in the journal Natural Plantsmay reveal the unexpected ways this global phenomenon is reshaping nature and our lives.

“What we see is that there is a connection between climate change and nutrition,” said Berkley Walker, an assistant professor in the Department of Plant Biology whose research team authored the new report. “This is something we don’t know that we will look into when we start.”

Although high levels of carbon dioxide can be good for photosynthesis, Walker and his lab also showed that increased CO2 levels can play havoc with other metabolic processes in plants. And this little-known process could have implications for other functions like protein production.

“Plants like CO2. If you give them more, they’ll make more food and they’ll grow bigger,” said Walker, who works in the College of Natural Sciences and MSU-Department of Energy Plant Research Laboratory. “But what if you get bigger plants which has lower protein content? It would actually be less nutritious.”

It’s too early to say for sure whether plants face a low-protein future, Walker said. But the new research raises surprising questions about how plants will make and metabolize amino acids—which are the building blocks of protein—with more carbon dioxide around.

And the harder we work to address that question now, the better prepared we will be for the future, said the report’s first author and postdoctoral scholar, Xinyu Fu.

“The more we know about how plants use different metabolic pathways under changing environments, the better we can find ways to manipulate metabolic flows and ultimately engineer plants to be more efficient and nutritious,” Fu said.

If at first the plant does not succeed, there is photorespiration

The basics of photosynthesis are well-known simply: Plants take water and carbon dioxide from their environment, and with the power of sunlight, convert those substances into sugar and oxygen.

But sometimes this process starts off on the wrong foot. Enzymes responsible for accumulating carbon dioxide can instead capture oxygen molecules.

This creates uncontrolled byproducts—essentially suffocating the plant, Walker said. Thankfully, however, plants have evolved a process called photorespiration that cleans up harmful byproducts and allows enzymes to take another swing at photosynthesis.

Photorespiration is not as well known as photosynthesis, and it sometimes gets a bad rap because it takes up carbon and energy that could be used to make food. Although it may be inefficient, photorespiration is better than the alternative.

“It’s like recycling,” Walker said. “It would be nice if we didn’t need it, but as long as we produce waste, we might as well use it.”

To carry out its task, photorespiration incorporates carbon into other molecules or metabolites, some of which are amino acids, precursors to proteins.

“So photorespiration is not just recycling, it may be recycling,” Walker said.

There’s a reason Walker used “maybe” instead of “is” in his statement. Photorespiration still holds some mysteries, and the fate of its metabolites is one of them.

Metabolic sleuthing

When it comes to where the amino acids produced by photorespiration end up, one established theory is that they remain in a closed loop. This means that the metabolites created in the process are limited to a select group of organelles and biochemical processes.

Now, MSU researchers have shown that that’s not always the case. In particular, they have shown that the amino acids glycine and serine are able to escape the confines of the closed loop.

What the compounds end up being is a lingering question and one that could become increasingly important as carbon dioxide levels rise.

Plants breathe less when more carbon dioxide is available, so scientists need to delve deeper into how plants produce and use these amino acids as a whole, Walker said.

For now, though, he and his team are excited that they’ve made this discovery, which is no small feat. It involves giving the plant a special type of carbon dioxide in which the carbon atom has one more neutron than the carbon normally found in the atmosphere.

Neutrons are subatomic particles, and therefore, they have a very small mass. If you take a paper clip, cut it into a trillion pieces and then cut one of those pieces into another trillion pieces, the smallest piece will have the same mass as a neutron.

But the MSU collaboration has the tools and expertise needed to measure such subtle mass differences. Those measurements, coupled with computational modeling, allowed the researchers to follow that lean carbon and see how plants integrate it at different metabolic stages when conditions favor photorespiration.

“This new technique enables a better and more quantitative understanding of important metabolic pathways in plants,” Fu said. “With the new flux approach, we have begun to reveal the dynamic state of metabolic pathways and understand metabolism as a whole system.”

“I said that my lab could do this in my job application, but I wasn’t sure it would work,” said Walker, who joined MSU in 2018. The fact that it worked is a credit to the team on the paper, which also includes graduate student Luke Gregory and research assistant professor Sean Weise.

But other colleagues at MSU also helped, including University Distinguished Professor Thomas Sharkey, Professor Yair Shachar-Hill and the team at the Mass Spectrometry and Metabolomics Core.

“Coming to MSU uniquely allows this to happen,” Walker said.

More information:
Xinyu Fu et al, Integrated flux and pool size analysis in plant central metabolism reveals unique roles of glycine and serine during photorespiration, Natural Plants (2022). DOI: 10.1038/s41477-022-01294-9

Provided by Michigan State University

Quote: Researchers uncover potential climate change-nutrition link in plant metabolism (2022, December 22) retrieved December 23, 2022 from https://phys.org/news/2022-12-uncover-potential-climate-change-nutrition-metabolism.html

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