A Matter of Microbes

When it comes to determining whether plants thrive or falter in a changing world, little things may make a big difference.

Are you having a good day? Chances are you have a plant to thank. Whether it’s food, a breath of fresh air or a healthy ecosystem, human well-being is intricately intertwined with that of the vegetation that greens our planet. The well-being of plants, in turn, depends on us. And, researchers are increasingly recognizing, it also depends on a less obvious but vastly important supporting cast: a diverse and bustling assemblage of bacteria, viruses and fungi that live within the plants themselves.

Some members of this “microbiome” are disease organisms we might rather get by without such as rusts and rots. But others are integral to function, helping plants use water, fight enemies and carry out the many other processes that allow them to thrive. Whether they help or harm, understanding the microbes within is key to understanding how we can encourage domestic plants to deliver their best in food, fiber and fuel to a growing global population in the face of global change.

An interdisciplinary team of University of Minnesota scientists is on it. Led by College of Biological Sciences community ecologist Elizabeth Borer, the team – which includes plant ecologist Eric Seabloom, evolutionary biologist Georgiana May and microbial ecologist Linda Kinkel of the College of Food, Agricultural and Natural Resource Sciences – just received a $1.5 million National Science Foundation grant to investigate factors that influence plant microbiomes, as well as how the microbiomes affect plants’ ability to thrive in a changing world.

The researchers plan to explore three aspects of plant-microbiome interactions: what factors influence the makeup of microbiomes, how microbiomes affect plant reproduction and disease susceptibility, and how microbiomes influence the transmission of microbes from one plant to another. Their research will focus on viruses, bacteria, and fungi in wild and crop grasses. Grasses, such as corn, wheat, and barley, make up the bulk of the human food supply, Borer notes, so this international research has long-term bearing on efforts to ensure food security for a growing population, both in Minnesota and around the world.

“We know that disease-causing microbes cause substantial losses to global crop yields,” Borer says. “There may be ways to manipulate the plant microbiome to increase resistance of crops to diseases and reduce reliance on pesticides.” Similarly, understanding the connections between the microbiome and herbivory will provide important insights for reducing loss of crops to other organisms, and capturing the links between the microbiome and nutrients will provide information farmers can use to fine-tune inputs for maximum gain.

Central to the four-year study will be experiments conducted at an international network of study sites Borer and Seabloom set up several years ago. Headquartered at the University of Minnesota and supported by Cedar Creek Ecosystem Science Reserve — a Long-Term Ecological Research site — and the U of M's Institute on the Environment, the Nutrient Network, known as NutNet, provides a framework for replicating studies across 69 study sites on six continents. For the microbiome study, researchers will expose native grasses and domestic barley to varying levels of two factors humans are changing worldwide: nutrients and exposure to plant-eating animals — rabbits, deer, elephants or kangaroos, depending on the setting. They’ll observe how the microbiome varies with conditions.

Why the international approach?

“The human impacts on the environment are global,” Seabloom says “We need to understand the way the world works. We can’t understand the way the world works at just one place.”

— Mary Hoff