Unique CO₂-Concentrating Mechanism Drives the Future of Sustainable Agriculture

Researchers have been exploring methods to enhance the ability of plants to convert carbon dioxide (CO₂) into biomass, a process that could increase crop yields and contribute to climate change mitigation. Recent studies indicate that a distinctive group of plants known as hornworts, which are frequently underestimated, may provide a solution.

Hornworts possess a remarkable ability that is unique among land plants: they have a natural turbocharger for photosynthesis. This special feature, called a CO₂-concentrating mechanism, helps them photosynthesize more efficiently than most other plants, including our vital food crops.”

Tanner Robison, Graduate Student and Study First Author, Boyce Thompson Institute

The study was published in the journal Nature Plants.

Central to this mechanism is a structure known as a pyrenoid, which functions as a microscopic chamber for concentrating CO₂ within the plant's cells. The pyrenoid is a gel-like compartment filled with the enzyme Rubisco, responsible for capturing CO₂ and transforming it into sugar during photosynthesis.

Encircling the pyrenoid are specialized channels and enzymes that facilitate the influx of CO₂, ensuring that Rubisco is saturated with this essential substrate.

This CO₂-concentrating mechanism gives hornworts a significant advantage. Rubisco is an infamously inefficient enzyme, so most plants waste a lot of energy dealing with its tendency to also react with oxygen. But by concentrating CO₂ around Rubisco, hornworts can maximize its efficiency and minimize this wasteful ‘photorespiration’ process.”

Laura Gunn, Assistant Professor, School of Integrative Plant Science, Cornell University

Through the use of advanced imaging techniques and genetic analysis, the research team discovered that hornworts likely employ a more straightforward mechanism for concentrating CO₂.

In contrast to algae, which rely on intricate systems to actively transport CO₂ into their cells, hornworts are thought to utilize a passive method that involves fewer components.

It is like finding a simpler, more efficient engine design. This simplicity could make it easier to engineer similar systems in other plants, like essential crops.”

Fay-Wei Li, Associate Professor and Study Co-Corresponding Author, Boyce Thompson Institute

The potential impact is considerable. The research team estimates that implementing a similar CO₂-concentrating mechanism in crops could enhance photosynthesis by as much as 60%, resulting in significant yield increases without the need for additional land or resources.

Furthermore, the research sheds light on plant evolution. The scientists discovered that the mechanism for concentrating CO₂ was likely present in the common ancestor of all terrestrial plants, but only hornworts have preserved and refined this capability over millions of years of evolution.

In facing the dual challenges of climate change and food security, this small plant may provide a blueprint for significant agricultural innovation. Although considerable work is still needed before this natural technology can be applied to other plants, the findings present a promising new avenue for sustainable agriculture.