College of Agriculture and Life Sciences faculty Madan Bhattacharyya and Aaron Gassmann are among six Iowa State University researchers the American Association for the Advancement of Science (AAAS) named this week to its class of 2021 Fellows for their “distinguished efforts to advance science or its applications.” They will be recognized at the AAAS’ annual meeting, planned for February 17-20.
Madan Bhattacharyya: Identifying genetic mechanisms to fight soybean diseases
Bhattacharyya, professor in the Department of Agronomy, is being honored for his “distinguished contributions to the field of plant-microbe interactions, particularly for understanding interactions between soybean and its fungal and oomycete pathogens.”
Bhattacharyya’s career has focused on studying the molecular basis of two important soybean diseases: sudden death syndrome (SDS), caused by the fungal pathogen Fusarium virguliforme, and root and stem rot disease, caused by the oomycete Phytophthora sojae. His lab has made significant contributions to understanding how the pathogens function and how soybean resists infection.
The team’s achievements include cloning a gene resistant to root and stem rot disease and mapping many disease-resistance genes in soybean. They sequenced the genome of F. virguliforme and identified its major SDS-causing toxin. They created a plant antibody from a mouse gene, and then synthetic plant antibodies that can sequester the SDS toxin and enhance SDS resistance in transgenic soybean lines.
Bhattacharyya’s research has shown that overexpression of three soybean genes that F. virguliforme infection suppresses can significantly enhance resistance. One of the genes not only boosts soybean resistance to SDS, but also to soybean aphids, spider mites and soybean cyst nematode.
“We are on the verge of publishing some exciting results on this research,” Bhattacharyya said. “This gene functions like a sort of ‘master switch’ that can be manipulated to enhance resistance against a broad spectrum of pathogen and pests.”
Another related area of his team’s research is studying resistance in the nonhost plant Arabidopsis. They have cloned five genes which can confer the nonhost immunity of Arabidopsis to help soybean resist the SDS pathogen.
Interest in plant-pathogen interactions started early for Bhattacharyya, who grew up in India. He said his “eyes were opened wide” in a senior undergraduate class at Assam Agricultural University, where he was introduced to Flor’s gene-for-gene hypothesis. The concept helps explain how corresponding disease-resistant genes in plants and disease-causing genes in pathogens determine resistance or susceptibility. “I never looked back after that day,” he said.
In graduate school, he worked on the biochemical basis of interactions between soybean and the pathogen causing root rot disease. That was when he started to recognize the soybean’s importance to sustain a nutritious food supply for people worldwide.
After earning a doctorate in plant sciences at the University of Western Ontario, Canada, in 1987 Bhattacharyya did postdoctoral work at the John Innes Centre in the U.K. and the Noble Foundation, Oklahoma. He started his lab in Noble Foundation in 1992 and joined Iowa State in 2000.
Since then, his research has received more than $10 million in support from funders, including the U.S. Department of Agriculture National Institute of Food and Agriculture, the Iowa Soybean Association, the United Soybean Board, the North Central Soybean Research Program, the Consortium of Plant Biotechnology Research, and Syngenta.
He is currently on the editorial board of the journal BMC Genomics and is a guest editor for the journals Frontiers in Plant Science, Frontiers in Chemistry and Agronomy. He is a member of the International Society for Molecular Plant-Microbe Interaction, the American Association for the Advancement of Science and the American Society of Plant Biology.
Aaron Gassmann: Researching insect-plant interactions for corn sustainability
Aaron Gassmann, professor in the Department of Entomology, was elected an AAAS Fellow, “for distinguished contributions to the field of entomology, particularly for advances in understanding the evolution of resistance by insect pests and approaches to delay pest resistance to transgenic crops.”
Much of his career has focused on interactions between the western corn rootworm and transgenic crops that incorporate insecticidal toxins like Bacillus thuringiensis, or Bt.
“I like to think of my work as using principles of evolutionary biology and ecology to enhance the sustainability of agriculture,” he said.
Western corn rootworm is one of the most serious pests of corn in Iowa and the Midwest. Beginning in 2003, Bt corn became available to help manage this pest. The technology was rapidly adopted by farmers because it was so easy to use, but the rootworm has been able to develop a fairly rapid counterresponse, Gassmann said.
“The western corn rootworm has been referred to as the billion-dollar bug -- and that was in the 1980s," he said. "Current estimates suggest the economic impact of this pest is double that amount."
Gassmann uses lab and field-based studies to explore factors that affect the risk of western corn rootworm evolving Bt resistance and approaches farmers can take to delay resistance. He developed the standard assay, or test, used across the Corn Belt to measure levels of Bt resistance by western corn rootworm.
A paper that reviews more than a decade of his work to identify factors affecting Bt resistance was recently published in the scientific journal, Insects.
Gassmann came to Iowa State in 2008, after completing postdoctoral work at the University of Arizona and the University of California-Riverside. He earned his doctoral degree in ecology and evolution from the State University of New York at Stony Brook and has a bachelor's degree in biology from the University of St. Thomas in Minnesota.
Among career accomplishments he’s especially proud of has been starting a collaborative effort to develop recommendations on managing pest resistance for farmers within the corn-growing states. The effort has involved working with a number of other scientists who are part of a U.S. Department of Agriculture Multi-State Research project focused on managing insect pests of corn. Much of his work has been funded through USDA National Institute of Food and Agriculture Biotechnology Risk Assessment grants.
Gassmann’s awards include the Early Achievement in Research Award (2012) from Iowa State’s College of Agriculture and Life Sciences and the DuPont Young Professor Award (2011), recognizing his work with industry to manage pest resistance. He is a member of several professional organizations including AAAS and the Entomological Society of America, for which he’s served as an editor for the Journal of Economic Entomology since 2014.
In addition to research, he teaches several courses and serves as faculty for interdisciplinary programs in Sustainable Agriculture and Ecology and Evolutionary Biology.