UMass Amherst Study Looks at Drought and Virus Impact on Plant Roots and Soil Carbon

Marco Keiluweit
Marco Keiluweit

AMHERST, Mass. – The U.S. Department of Energy (DOE) recently awarded biogeochemist Marco Keiluweit, assistant professor of soils and the environment in the Stockbridge School of Agriculture at the University of Massachusetts Amherst, and his collaborators elsewhere, two grants to study how climate change affects the capacity of soils to remove carbon from the atmosphere and retain enough nutrients for food production.

In particular, the teams will investigate climate change-related effects of drought and virus infection in plants, and their interaction with soils. Keiluweit and colleagues received $200,000 and $300,000 exploratory research awards from DOE’s Biological and Environmental Research program, which supports “high-risk, high-reward” research, the soil chemistry expert says.

“It’s basic science to develop a better understanding of the processes that sequester carbon in soils to put us in a better position to predict how soils may respond to climate change,” Keiluweit explains. “Plant root-soil interactions are important for two crucial functions of soils – carbon storage and agricultural production – but we don’t really understand how they are being altered by climate change. For example, prolonged droughts or increased virus-infections can severely impact plants, with unknown consequences for root-soil interactions.”

Keiluweit’s collaborators include Zoe Cardon at the Woods Hole Marine Biology Laboratory, the principal investigator on one of the grants, and Malak Tfaily at the University of Arizona, Carolyn Malmstrom at Michigan State University and William J. Riley at Lawrence Berkeley National Laboratory.

Their drought-focused research will look at plants in an alpine watershed near Gothic, Colorado, where root-soil interactions are key regulators of ecosystem carbon storage and downstream nutrient loadings, the researchers say. These areas have been shown to be particularly vulnerable to climate change, they point out.

For this work, Keiluweit says he and collaborators will make “very fine scale measurements of what is happening at the interface between roots and soil” in both greenhouse and field experiments. They want to explore what they call “elusive mechanisms” driving root-soil interaction, which may mobilize a “vast pool of organic matter that has been stabilized by associations with minerals for centuries or millennia.” Such mechanisms are missing from conceptual and numerical models of carbon cycling in soils, they note.

Keiluweit says, “Roots try to manipulate the soil environment to make it more habitable for themselves. They fix carbon from the atmosphere and send it to the root, where it is released as organic carbon compounds into what we call the rhizosphere – the soil surrounding the root – to reshape it to their needs for water, nutrients and minerals, and to attract beneficial microbes and suppress harmful ones.”

He adds, “We’re learning more and more about the rhizosphere and the intricate interactions that take place between roots and microbes. We think there is a synergistic interplay that allows them to mobilize organic matter, which is rich in carbon and nutrients, from minerals. Micro-scale measurements will allow us to reveal more of this interplay and how it relates to soil carbon storage and fertility.”

For the virus-focused work, Keiluweit will collaborate on a project led by principal investigator Cardon to study the effects of plant viruses on the rhizosphere. In collaboration with DOE’s Environmental Molecular Science Laboratory at Pacific National Research Laboratory, Richland, Washington, that provides a suite of advanced characterization techniques, they will investigate how virus infection of plants affects the types and reactivity of carbon compounds roots release into the soil environment. 

Further, they will explore for the first time whether plant virus infection can serve as a tool to intensify the release of such compounds from roots, potentially enhancing microbial activity or liberating organic matter from minerals. The researchers point out, “Viral infection is widespread in terrestrial ecosystems; 25-70 percent of plants have virus infection, yet the influence of such infection on root traits and terrestrial soil carbon dynamics remains largely unexplored.”