This odd little plant could help turbocharge crop yields

(Press-News.org) An international team of researchers has uncovered a remarkable molecular trick used by a unique group of land plants, one that could eventually be engineered into crops like wheat and rice to dramatically boost how efficiently they convert sunlight into food.

The study, led by researchers at the Boyce Thompson Institute (BTI), Cornell University, and the University of Edinburgh, focuses on a fundamental problem in agriculture: the enzyme responsible for capturing carbon dioxide from the air during photosynthesis—called Rubisco—is slow and inefficient.

"Rubisco is arguably the most important enzyme on the planet because it's the entry point for nearly all carbon in the food we eat," said BTI Associate Professor Fay-Wei Li, who co-led the research. "But it's slow and easily distracted by oxygen, which wastes energy and limits how efficiently plants can grow."

Some organisms have evolved a clever workaround. Many species of algae pack Rubisco into tiny, specialized compartments inside their cells called pyrenoids—essentially microscopic bubbles that concentrate carbon dioxide around the enzyme, helping it work far more efficiently.

Scientists have long dreamed of installing this turbocharging system into food crops, which lack pyrenoids. But algae machinery has proven stubbornly difficult to transfer.

The breakthrough came from studying hornworts—the only land plants known to possess CO₂-concentrating compartments similar to those in algae. Because hornworts share a more recent evolutionary history with crops than algae do, the research team hypothesized their molecular machinery might transfer more readily. What they found was unexpected.

"We assumed hornworts would use something similar to what algae use—a separate protein that gathers Rubisco together," said Tanner Robison, a graduate student working with Li and a co-first author of the paper. "Instead, we discovered they've modified Rubisco itself to do the job."

The key is an unusual protein component the researchers have named RbcS-STAR. Rubisco is assembled from large and small protein pieces. In hornworts, one version of the small piece carries an extra tail—the STAR region—that acts like molecular velcro, causing Rubisco proteins to constellate.

To test whether STAR could work outside its native hornwort, the team conducted a series of experiments. First, they introduced RbcS-STAR into a closely related hornwort species that lacks pyrenoids. The result: Rubisco reorganized from a scattered distribution into concentrated, pyrenoid-like structures.

They then tried the same experiment in Arabidopsis, a plant commonly used in lab research. Again, Rubisco formed dense compartments inside the plant's chloroplasts.

"We even tried attaching just the STAR tail to Arabidopsis's native Rubisco, and it triggered the same clustering effect," said Alistair McCormick, professor at the University of Edinburgh, who co-led the research. "That tells us STAR is truly the driving force. It's a modular tool that can work across different plant systems."

This transferability is what makes the finding so significant for agriculture. It suggests that researchers may be able to trigger Rubisco clustering in crop plants by introducing a single universal velcro, rather than going through haute couture.

The researchers note that challenges remain. A series of ductwork are now needed to deliver CO2 to Rubisco. "We have built a Rubisco house, but it won’t be an efficient house unless we update the HVAC," said Laura Gunn, assistant professor at Cornell University, who co-led the research. The team is now working to address this challenge.

Still, the discovery marks an important advance in a field with enormous potential impact. Improving photosynthetic efficiency even modestly could increase crop yields while reducing agriculture's environmental footprint—a crucial goal as the world works toward more sustainable food production.

"This research shows that nature has already tested solutions we can learn from,” said Li. “Our job is to understand those solutions well enough to apply them where they're needed most—in the crops that feed the world."

The study was published in Science, with equal contributions from four early-career scientists: Tanner A. Robison, Yuwei Mao, Zhen Guo Oh, and Warren S.L. Ang. The corresponding authors were Laura H. Gunn, Alistair J. McCormick, and Fay-Wei Li.
 

About the Boyce Thompson Institute (BTI)
As an independent nonprofit research institute affiliated with Cornell University, our scientists are committed to advancing solutions for global food security, agricultural sustainability, and human health. Through groundbreaking research, transformative education, and rapid translation of discoveries into real-world applications, BTI bridges fundamental plant and molecular science with practical impact. Discovery inspired by plants. Learn more at BTIscience.org.

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