Researchers have discovered a gene that could make plants grow deeper root systems, equipping them not only to cope with drier climates, but also to store more carbon—and thereby, actively fight climate change.
The findings, published in Cell, emerged from a research collaborative called the Harnessing Plants Initiative, which seeks to leverage the natural power of plants to capture carbon dioxide from the air. Focusing on the thale cress—a widely-used plant model—the Salk Institute researchers wanted to uncover the mechanism behind the behavior of a particular plant hormone called auxin, which is well known to control general plant growth, as well as root development.
They discovered that just a single gene—called EXOCYST70A3—regulates auxin’s role in root development, specifically. By studying variants of this gene, they could show it was associated with changes in the roots of individual plants – and that in particular, it could enable some to actually grow longer, and reach deeper into the soil. By pinpointing one specific gene, researchers have, crucially, found a way to target the behavior of the hormone auxin only when it comes to the root-growing process – without disrupting other crucial aspects of plant growth that the hormone is tied to.
This discovery could be hugely significant in our efforts to grapple with climate change. The carbon than plants suck out of the air gets stored within their root systems, in the form of a substance called suberin. One fortuitous benefit of suberin is that it doesn’t decompose, meaning that roots can keep carbon on lockdown, within the soil, instead of letting it escape into the atmosphere. So, it follows that the larger that root system grows, and the deeper it plunges onto the soil, the more carbon a plant can suck out of the atmosphere, and store securely within this dense underground architecture.
“Plants have evolved over time to be the perfect vehicle for carbon capture and storage,” the researchers write on their website. By tweaking them to become even better at this task, we could potentially mitigate the most acute cause of anthropogenic climate change.
This first major discovery from the Harnessing Plants Initiative is also the first step towards its ambitious, larger goal of finding multiple genetic pathways that influence root development and boost suberin content in plants. But the aim isn’t just to reduce levels of atmospheric CO2, the researchers explain.
Their recent discovery could also potentially be applied to engineer crops that are equipped to grow in dry, harsh environments where food insecurity is rife. The study also showed that variants of the EXOCYST70A3 gene caused plants not only to grow deeper roots, but to reorient their root systems, too. That could enable us to engineer plants that develop horizontal, shallow-growing roots, nearer the surface, in places where rainfall is sporadic and light – enabling them to make the best use of scarce resources when they’re available. Alternatively, plants engineered to grow deep-reaching roots could plumb the depths for water, which could be a boon in regions that are routinely hit by drought.
As the researchers with the Harnessing Plants Initiative develop more ways to determine root growth, they’ll also be looking ultimately into engineering crops like wheat, soya, and rice to have these climate-resilient traits.
For now, the researchers’ sights are set on equipping plants with a greater capacity to slurp up CO2 and store it away. Who knows—maybe in the future, the trees we plant, the gardens we grow, and crops we seed could be foot soldiers in our battle against climate change.
