Spring 2001 -- Vol. 18, No. 1

FACES OF PENN STATE

Sally Assmann
Professor of Biology

Professor Sally Assmann studies guard cells on the epidermal layer of plant leaves. Through her research she hopes to understand how plants respond to stimuli and, possibly, to be able to control that response.

Sally Assmann makes no apologies. She understands most people probably expect a professor who studies plants to have either a nice garden or lush house plants.

She has neither.

"At the moment there's no garden and the nicest plants in the house, really the only plants in the house, belong to my son," Assmann says. "He has an interest in carnivorous plants."

Assmann's interest in plants could be considered superficial. After all, she studies guard cells located on the surface of plant leaves.

However, the role of those cells in the epidermal layer is anything but superficial. They help control almost every aspect of a plant's life. Through her research about guard cell responses to environmental and internal signals, Assmann hopes to unlock the secrets of plant behavior. Eventually, she hopes to engineer guard cells so plants can be designed to respond in predictable ways. Because of the complexity and diversity of the cells, her work provides constant challenges.

"These cells are more complex than a lot of others because they do so many things," Assmann says. "In our bodies, certain cells have certain responsibilities but in plants, with these guard cells, the same cells act and respond to carry out a multitude of tasks."

In response to the presence of water or the lack of water, or in response to light or other stimuli, guard cells control the opening and closing of pores on leaves that help moderate the amount of water and carbon dioxide in the plant. The guard cells balance the plant's priorities.

Among many potential practical applications are uses for farmers. For example, if biologists can engineer crop plants, farmers might be able to better control how the plants respond to the weather during the growing season. Also, if the opening and closing of pores on plant leaves can be controlled, farmers might be able to alter the percentage of water in their crop when they take it to market. Water content plays an important role in determining the quality and value of the crop.

Ironically, Assmann gravitated to plant biology because of her love of animals. "For a while my focus was going to be neurobiology, but among my realizations was that in order to get to a certain level with my research, a large number of animals might have to be sacrificed," Assmann says. "That's not something that appealed to me."

During her graduate years at Stanford University, in a department organized much like the Department of Biology at Penn State--"The diversity of all the different types of biology made it a good place to experience different fields and for people to collaborate," she says--Assmann began to concentrate on plant biology. As a professor, her enthusiasm for her work and her willingness to collaborate have served both her and the department well.

"It's the surprises, when you discover something new to human knowledge, that are the most enjoyable," Assmann says. "When that happens, it's incredibly rewarding."

-- By Steve Sampsell

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