This odd little plant could help turbocharge crop yields

A study has revealed a remarkable molecular trick, used by a unique group of land plants, that could eventually be engineered into crops like wheat and rice to dramatically boost how efficiently they convert sunlight into the food that fuels their growth.

The discovery marks an important advance with enormous potential impact. Improving photosynthetic efficiency even modestly could increase crop yields while reducing agriculture's environmental footprint - making global food production more sustainable.

The researchers focused on a fundamental problem in agriculture: the enzyme responsible for capturing carbon dioxide and turning it into sugar during photosynthesis—called Rubisco—is slow and inefficient in most plants.

The breakthrough, discovered by researchers at the Universiity of Edinburgh, Boyce Thompson Institute (BTI) and Cornell University, came from studying hornworts—the only land plants known to possess CO₂-concentrating compartments.

It was already know that nature had evolved a clever workaround. Many species of algae pack Rubisco into tiny, specialized compartments inside their cells called pyrenoids— 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.

Because hornworts share a more recent evolutionary history with crops than algae do, the team hypothesized their molecular machinery might transfer more readily.

They discovered that the key is an unusual protein component they 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.

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.

However challenges remain and the team are now working on a series of ductwork that is now needed to deliver CO2 to Rubisco.

The study, published in Science, was funded by National Science Foundation, the Environmental Molecular Sciences Laboratory, the Triad Foundation, Schmittau-Novak, UK Research and Innovation (UKRI), Biotechnology and Biological Sciences Research Council (BBSRC), the Bill & Melinda Gates Foundation and the United Kingdom Foreign, Commonwealth and Development Office

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. But it's slow and easily distracted by oxygen, which wastes energy and limits how efficiently plants can grow. The research shows that nature has already tested solutions we can learn from. Our job is to understand those solutions well enough to apply them where they're needed most—in the crops that feed the world.

We tried attaching just the STAR tail to Arabidopsis's native Rubisco, and it triggered the same clustering effect. That tells us STAR is truly the driving force. It's a modular tool that can work across different plant systems.

We assumed hornworts would use something similar to what algae use—a separate protein that gathers Rubisco together. Instead, we discovered they've modified Rubisco itself to do the job."

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