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Plant scientist Walter Gassmann latest CAFNR researcher to earn AAAS Fellow honors

Walter GassmannWalter Gassmann

As Walter Gassmann tells it, he is a biologist who happens to have a growing appreciation for plants as his career has progressed.

“I really appreciate the puzzle aspect of science and working to find how the pieces fit together and the approach that science takes to answering those kind of questions,” Gassmann said. “Sometimes I think I could almost work on anything that uses that kind of process, but I’m really glad I’m working on plants because I think they are fascinating organisms in their own right.”

Growing up as the son of a Swiss cotton broker in Karachi, Pakistan, Gassmann from an early age was aware of the importance that plants have for human welfare. He did not begin to develop a passion for plant research, though, until he conducted electrophysiology experiments to study small currents in plant membranes while working on his doctorate degree in plant biology at the University of California, San Diego.

Gassmann, a professor in the Division of Plant Sciences, was recently elected as a Fellow of the American Association for the Advancement of Science (AAAS). He specializes in molecular plant pathology in his laboratory at the Bond Life Sciences Center. Since arriving at University of Missouri’s College of Agriculture, Food and Natural Resources in 2000 as an assistant professor, Gassmann has been a member of the Interdisciplinary Plant Group (IPG).

He was elected in the section of Agriculture, Food and Renewable Resources “for outstanding and seminal contributions to plant pathology in the area of plant innate immunity and cellular responses to pathogen exposure.” Gassmann was nominated by Melvin Oliver, a fellow IPG team member and adjunct professor of plant sciences — as well as a supervisory research geneticist with the USDA Agricultural Research Service — who became an AAAS Fellow in 2014.

 “I was pleasantly surprised,” said Gassmann, who earned the CAFNR Outstanding Graduate Advisor Award earlier this year and has been the associate editor of the journal Plant Molecular Biology since 2013. “I felt very honored, especially that one of my colleagues went to the trouble of nominating me. We’re all really busy and to take time out of their schedule… but that’s how I feel this place works.”

“I felt very honored, especially that one of my colleagues went to the trouble of nominating me. We’re all really busy and to take time out of their schedule… but that’s how I feel this place works.”
― Walter Gassmann

Gassmann will be formally recognized with the rest of the recent inductees — including fellow MU researcher and IPG colleague Kathleen Newton, a professor in the Division of Biological Sciences, and Dr. Edward T.H. Yeh, the chair of the Department of Medicine in the School of Medicine — at the AAAS Annual Meeting Feb. 18 in Boston, where they will receive a gold and blue rosette pin to symbolize the synergistic nature of science and engineering.

Gassmann’s and Newton’s acceptance brings the number of AAAS Fellows in the IPG to 22. Gassmann becomes the sixth member in the Division of Plant Sciences to receive the recognition — a list that includes IPG director Bob Sharp, and Jack Schultz, the director of the Bond Life Sciences Center.

“Walter has proven to be a vital member of our division,” said Jim English, director of the Division of Plant Sciences. “His devotion to his research and his constant efforts to collaborate with members of the plant sciences community make him a natural selection for an honor of such acclaimed national recognition.”

Tracing its roots back to 1848, the AAAS is an international non-profit organization dedicated to advancing science around the world. Its mission is to “advance science, engineering, and innovation throughout the world for the benefit of all people.” Fellows are nominated by a group of their peers in recognition for their advancement of a particular field of science.

The Columbia strain

For years, Gassmann and his lab team have been working on studying the resistance of pathogens for a variety of plants. Most of their energy has gone toward developing a better understanding of the model plant, Arabidopsis — the first plant to be fully genetically sequenced. It was popularized by a former MU plant geneticist, George Rédei , in the ’50s and ’60s, who ended up creating numerous mutant versions of the plant during that time.

As a result the most popular strain of Arabidopsis used for research is called “Columbia,” as a tribute from Rédei to the city where he conducted his work.

Morgan Halane, a graduate student who works in Walter Gassmann's lab in the Bond Life Sciences Center, smashes an Arabidopsis sample with a tiny pestle. Photo by Caleb O'Brien.Morgan Halane, a graduate student who works in Walter Gassmann’s lab in the Bond Life Sciences Center, grinds an Arabidopsis sample with a tiny pestle. Photo by Caleb O’Brien.

“I’m always surprised how few people in my field know that. They work with Columbia but have no idea,” said Gassmann, who added that the most common guess usually involves Columbia University in New York.

Gassmann and his team are now on the second year of three-year, $998,000 grant from the National Science Foundation to continue to learn the intricacies of the plant’s regulatory system. These intricacies were first discovered through a mutant screen (a process used by geneticists to find the building blocks needed for a particular biological process, which in this case, are tied to the immune system).

Gassmann studies the signal transduction of plant cells by looking at the receptors inside them, which he calls the second line of defense to pathogens.

“Once a pathogen has breached the first line of defense it actually shoots proteins into the plant cell to manipulate the host cell and that’s the level we are working on,” Gassmann said. “My view is that we really have to understand the response network that comes downstream of those receptors so we can have durable resistance in crop plants, something that the pathogen cannot overcome and that’s why it’s so important to understand how the signaling actually works because once we understand the network, then we can tweak it to make it more robust and more efficient.”

Samples of Arabidopsis plants.Samples of Arabidopsis plants.

Key to this research is an adaptor protein gene called SRFR1, a.k.a. “Surfer One.” In addition to regulating plant immune systems, the gene appears to be important in integrating different stress signals and balance immune responses with growth and development. As Gassmann’s doctoral students Sang He Kim and Fei Gao discovered, Arabidopsis plants without SRFR1 lose their traditional shape and growth rate as the immune receptors become more active and the plants build their resistance levels to pathogens.

A master’s student of Gassmann’s from Saudi Arabia, Nadiyah Alamri, recently defended her thesis on the work she did after sequencing the SRFR1 gene — which can also be found in humans, mice, puffer fish and amoebas, among other organisms — in a tomato plant in the hope of one day seeing if the same relationship between SRFR1 and Arabidopsis holds true for tomatoes. The tomato plant could benefit the earliest from a translation from the lab to the field, Gassmann said.

While many insights from Arabidopsis research has been translated to crop plants, the heightened immunity traits are difficult to transfer to crops due to the resulting smaller plant size compared to those without any modifications. This difficulty often leads to a yield penalty “unless we understand how the whole system is regulated,” Gassmann said.

Still, Gassmann and others studying the plant immune system remain hopeful to be able to one day see the development of crop plants that possess a higher ability of immunity to pathogens while still growing to a hearty size and amount.

In the recent years, Gassmann has begun to develop an interest an vegetable crops — and the ability for farmers in developing countries to plant them — given their high nutritional value and short shelf life.

“They are best grown where the people need it,” Gassmann said, “and to do that without pesticides and fertilizer we really need to improve vegetables in those countries to make it easier for people to grow them.”