New research is trying to give plants stronger, deeper roots to make them scrub more CO2 out of the atmosphere.

Image via Pixabay.

Researchers at the Salk Institute are investigating the molecular mechanisms that govern root growth pattern in plants. Their research aims to patch a big hole in our knowledge — while we understand how plant roots develop, we still have no idea which biochemical mechanisms guide the process and how. The team, however, reports to finding a gene that determines whether roots grow deep or shallow in the soil and plans to use it to mitigate climate warming.

Deep roots are not reached by the scorch

“We are incredibly excited about this first discovery on the road to realizing the goals of the Harnessing Plants Initiative,” says Associate Professor Wolfgang Busch, senior author on the paper and a member of Salk’s Plant Molecular and Cellular Biology Laboratory and its Integrative Biology Laboratory.

“Reducing atmospheric CO2 levels is one of the great challenges of our time, and it is personally very meaningful to me to be working toward a solution.”

The study came about as part of Salk’s Harnessing Plants Initiative, which aims to grow plants with deeper and more robust roots. These roots, they hope, will store increased amounts of carbon underground for longer periods of time while helping to meaningfully reduce CO2 in the atmosphere.

The researchers used thale cress (Arabidopsis thaliana) as a model plant, working to identify the genes (and gene variants) that regulate auxin. Auxin is a key plant hormone that has been linked to nearly every aspect of plant growth, but its exact effect on the growth patterns of root systems remained unclear. That’s exactly what the team wanted to find out.

“In order to better view the root growth, I developed and optimized a novel method for studying plant root systems in soil,” says first author Takehiko Ogura, a postdoctoral fellow in the Busch lab. “The roots of A. thaliana are incredibly small so they are not easily visible, but by slicing the plant in half we could better observe and measure the root distributions in the soil.”

One gene called EXOCYST70A3, the team reports, seems to be directly responsible for the development of root system architecture. EXOCYST70A3, they explain, controls the plant’s auxin pathways but doesn’t interfere with other pathways because it acts on a protein PIN4, which mediates the transport of auxin. When the team chemically altered the EXOCYST70A3 gene, the plant’s root system shifted orientation and grew deeper into the soil.

“Biological systems are incredibly complex, so it can be difficult to connect plants’ molecular mechanisms to an environmental response,” says Ogura. “By linking how this gene influences root behavior, we have revealed an important step in how plants adapt to changing environments through the auxin pathway.”

“We hope to use this knowledge of the auxin pathway as a way to uncover more components that are related to these genes and their effect on root system architecture,” adds Busch. “This will help us create better, more adaptable crop plants, such as soybean and corn, that farmers can grow to produce more food for a growing world population.”

In addition to helping plants scrub CO2 out of the atmosphere, the team hopes that these findings can help other researchers understand how plants adapt to differences between seasons, such as various levels of rainfall. This could also point to new ways to tailor plants to better suit today’s warming, changing climate.

The paper “Root System Depth in Arabidopsis Is Shaped by EXOCYST70A3 via the Dynamic Modulation of Auxin Transport” has been published in the journal Cell.