If you remember your high school biology, you’ll recall that plants breathe in carbon dioxide and exhale oxygen. Of course, they don’t breathe quite the way humans do.

Botanists have known for more than 100 years that plant leaves have pores called stomata, and they have an intricate network of air channels to bring that carbon dioxide where it needs to go. But it wasn’t understood until recently how those channels form in the right places to give a steady flow of CO2 to every plant cell.

Scientists at England’s University of Sheffield are the ones who figured it out. They used genetic manipulation techniques to show that the more stomata a leaf has, the more air space it forms. These air channels act like bronchioles—the tiniest passages in human and animal lungs. According to the researchers, the discovery marks a major step forward in our understanding of leaves’ internal structures, the way plants breathe, and how the functions of tissues can influence how they develop.

“Until now, the way plants form their intricate patterns of air channels has remained surprisingly mysterious to plant scientists,” said Professor Andrew Fleming of the University of Sheffield’s Institute for Sustainable Food.

What’s more, the study also shows that wheat plants have been bred, perhaps unknowingly, by generations of humans to have fewer pores on their leaves and fewer air channels. This makes their leaves more dense and allows them to be grown with less water. It also shows the potential for scientists to create drought-stable staple crops like wheat, rice, and other grains.

“The fact that humans have already inadvertently influenced the way plants breathe by breeding wheat that uses less water suggests we could target these air channel networks to develop crops that can survive the more extreme droughts we expect to see with climate breakdown,” Sheffield said.

Researcher Dr. Marjorie Lundgren of Lancaster University said, “Scientists have suspected for a long time that the development of stomata and the development of air spaces within a leaf are coordinated. However, we weren’t really sure which drove the other. So this started as a ‘what came first, the chicken or the egg?’ question.”

The research team used X-ray CT image analyses to answer these questions using species with very different leaf structures. They found that the stomata actually need to be exchanging gases for the air spaces to expand.

So, there you have it. New knowledge of the way plants breathe has led to findings that could prove crucial in a time of accelerating climate change.

The scientists’ findings were published in the journal Nature Communications.

Photo: A close-up of a leaf showing its veins and structure. Credit: Shutterstock