Tiny Moss Cousin Could Boost Crop Yields by 60%

A tiny, overlooked plant might hold the key to feeding more people with less farmland, less water, and fewer chemicals.

Scientists have cracked the code of how hornwort, a moss-like plant that grows as a thin green sheet on the ground, makes photosynthesis work better than nearly every other plant on land. The secret involves a special protein that creates tiny compartments inside cells, pumping them full of carbon dioxide to turbocharge growth.

The breakthrough matters because all plants depend on an enzyme called rubisco to convert CO2 into sugars during photosynthesis. But rubisco is remarkably clumsy at its job. It often grabs oxygen instead of carbon dioxide, creating toxic waste and limiting how fast plants can grow.

This inefficiency forces farmers to use massive amounts of fertilizer and water. Plants need lots of rubisco to compensate for how poorly it works, which requires chemical fertilizers that pollute waterways and cost a fortune to produce. And because rubisco is so bad at capturing CO2, plants have to open their pores wider to breathe, releasing more water and requiring constant irrigation.

Hornwort evolved a workaround millions of years ago. It builds specialized structures called pyrenoids that concentrate CO2 around rubisco, keeping oxygen out. Think of it as putting the enzyme in a sealed room and flooding it with the exact gas it needs.

Some algae do this too, but they're too distantly related to crops for scientists to copy their method. Hornwort is much closer on the family tree to the foods we eat.

The research team, led by scientists at Cornell University and the Boyce Thompson Institute, identified the exact protein responsible. They call it RbcS-STAR, and it acts like a tail that helps rubisco enzymes link together into those beneficial compartments.

To test their discovery, the researchers genetically modified a related hornwort species that doesn't normally have pyrenoids. It worked. Then they tried it in Arabidopsis, a common lab plant used to test agricultural innovations. It worked again, creating pyrenoid-like structures.

Laura Gunn, a synthetic plant biologist at Cornell and study coauthor, said adding these structures to crops could boost growth and yields by as much as 60 percent. Robert Wilson, a biochemist at MIT who wasn't involved in the research, called it "very impressive" and a completely new mechanism for improving photosynthesis.

The researchers still have work to do. Right now they've built the structure, but they haven't yet installed the full system that pumps CO2 in and sugar out. Gunn compared it to building a house with walls and a roof but no HVAC system yet.

The Ripple Effect

Once complete, this technology could transform global agriculture. Farmers could grow the same amount of food on less land, reducing pressure to clear forests. They'd need far less synthetic fertilizer, cutting both costs and water pollution. And because plants could close their pores more often, they'd need less irrigation in a warming world where water is increasingly scarce.

The timing couldn't be better, since rising temperatures make rubisco even less efficient. As the planet heats up, this naturally evolved solution might help crops adapt and thrive.