Scientists have long explored methods to enhance plants’ ability to convert carbon dioxide (CO2) into biomass, a breakthrough that could not only boost crop yields but also address climate change. Recent research highlights hornworts, a group of often-overlooked plants, as a potential game-changer.
“Hornworts possess a remarkable ability that is unique among land plants: they have a natural turbocharger for photosynthesis,” said Tanner Robison, a graduate student at the Boyce Thompson Institute (BTI) and lead author of a study published in Nature Plants. “This special feature, known as a CO2-concentrating mechanism, allows them to photosynthesize more efficiently than most plants, including critical food crops.”
Laura Gunn, an assistant professor at Cornell University’s School of Integrative Plant Science, elaborated on the significance of this mechanism. “Rubisco, the enzyme responsible for capturing CO2, is notoriously inefficient. Most plants expend considerable energy managing its tendency to react with oxygen. Hornworts, however, overcome this limitation by concentrating CO2 around Rubisco, minimizing energy waste caused by ‘photorespiration.’”
The research team utilized advanced imaging techniques and genetic analysis to uncover that hornworts employ a simpler CO2-concentrating system compared to algae. Unlike algae, which rely on complex machinery to pump CO2 into their cells, hornworts likely use a passive approach, requiring fewer components.
“It’s like discovering a simpler, more efficient engine design,” explained Fay-Wei Li, associate professor at BTI and co-corresponding author of the study. “This simplicity could pave the way for engineering similar systems in essential crops.”
The implications are profound. Researchers estimate that integrating a comparable CO2-concentrating mechanism into crops could boost photosynthesis by up to 60%, leading to substantial yield increases without additional land or resources.
Beyond its practical applications, the study sheds light on plant evolution. The team found that the machinery for CO2 concentration likely existed in the common ancestor of all land plants. Over millions of years, hornworts refined and retained this ability, while other plants lost it.
At the core of this mechanism lies a structure called a pyrenoid, a liquid-like compartment packed with the enzyme Rubisco. The pyrenoid acts as a microscopic CO2 concentration chamber within the plant’s cells. Surrounding the pyrenoid are specialized channels and enzymes that saturate Rubisco with CO2, enabling efficient sugar production during photosynthesis.
This breakthrough research positions hornworts as a vital resource for enhancing crop efficiency and tackling global challenges like food security and climate change.
