College of Liberal Arts and Sciences at Iowa State University

Stressed out

USDA awards botany professor grant to study how plants respond to nutrient stresses
For plants of all shapes and sizes, environmental stress can come in the form of too much moisture or not enough precipitation.

It can be too cold or way too hot. Even the amount of light can come into play.

Some plants thrive in these extreme conditions. Others don't.

Now a new study by botany's Diane Bassham is looking at how plants respond to these environmental stresses.

"All plants have adapted to their natural environment," the assistant professor of botany said, "and most plants survive under some sort of environmental stress. It might be low light or cold temperatures that cause the plants not to perform photosynthesis efficiently.

"We're trying to find out what they do to survive that kind of stress."

The Iowa State plant scientist has received a three-year, $210,000 grant from the U.S. Department of Agriculture (USDA) to study how plants respond to nutrient stresses. She will study the changes that take place in the structure of a plant cell when insufficient nutrients are available. Bassham will identify the genes that control these responses and determine their role in the survival of plants under environmental stress.

Specifically, Bassham is looking at the role of the vacuole in plant responses to nutrient limitation. Plant cells typically contain a large central vacuole that is responsible for a variety of processes including protein degradation, storage of metabolites and proteins, maintenance of turgor pressure, and cell homeostasis.

"Upon exposure to certain stress conditions, non-essential cell components are broken down in the vacuole in order to recycle their constituents and maintain essential functions," Bassham says.

This occurs by a process called autophagy where portions of the cytoplasm are surrounded by membrane and delivered to the vacuole for degradation.

"I plan to use a variety of approaches to study the regulation and mechanism of autophagy," she said. "I would like to understand how plant cells perceive nutrient stresses, how the signal is transduced within the cell, and the ways in which the endomembrane system of the cell changes upon induction of vacuolar autophagy."

Bassham, who conducts research in the Center for Plant Responses to Environmental Stresses in the Plant Science Institute, says the research could lead to improved stress tolerance in corps.

"If we know how plants survive under these environmental stresses, then maybe we can start to modify plants to become even more resistant," she said.

Modifications could then be made on cash crops prevalent throughout Iowa and the Midwest, which lose up to 70 percent of yield to environmental factors. Bassham says the modifications could also be done on horticulture plants as well.

In her studies, Bassham utilizes the Arabidopsis mustard plant, a common weed that is typically utilized by plant biologists world wide to conduct such experiments. The genome of the Arabidopsis plant has been sequenced, making it a model system on which to conduct this type of research.