TransPlant Science

TransPlant Science

BTI researchers look to replicate plant disease suppression by understanding microbial communities in the soil

by Sarah Perdue
Crop loss due to disease is a major factor in the use of pesticides, but current BTI research is hoping to decrease pesticide use while also increasing crop yields. “We know that some soils are more disease suppressive than others, and the same crops grown in disease suppressive soil are healthier than those grown in normal soil,” said Zewei Song, a postdoctoral fellow in plant pathology. His work, which could lead to less pesticide runoff from farmland into lakes and streams, is funded in part by a MnDRIVE: Environment postdoctoral fellowship. “What is more amazing is you can inoculate this disease suppressive soil into sterile soil and this soil becomes disease suppressive,” Song added, likening this process to microbiota/fecal transplantation in humans, also being studied at the University. “We want to find the biological mechanisms that make soils disease suppressive and reproduce this outcome in agricultural fields.” Researchers have long known that competition amongst microbes plays an important role in antibiotic production and plant health, but studies have often focused on one species at a time, or interactions between only a few species. Song and his colleagues want to study the systems of soil microbes as a whole to better understand how their interactions lead to plant disease suppression. If they can understand how soil microbes suppress plant disease, then they can more quickly mitigate the effects of crop pathogens. “We’re adding carbon sources into the soil to increase competition, then we’re measuring plant disease, such as scab on potatoes, and sequencing the microbial communities to identify their structure,” Song said. “We’re trying to see if we can increase disease suppression with these carbon additions and understand the responses in the microbial community structure over time.” Linda Kinkel, Professor of Plant Pathology and lead investigator of the study, said the field study is in its second season so the microbial community structure changes have not yet been analyzed. “We saw good responses in terms of reductions in disease and enhancements in plant productivity during the first season of the study,” she added. Kinkel said that this project builds on a USDA-funded project, but without MnDRIVE they would only have had funding to investigate the effects of carbon amendments on the plants. “The USDA study allows us to measure the plant response to the treatments, but MnDRIVE provides the funds to collect data on shifts in soil community composition and diversity following treatment,” Kinkel said. “There’s synergy there. The whole really is greater than the sum of the parts.” Kinkel added that Scott Bates, former Assistant Professor in Plant Pathology and partner on the project, has contributed significant expertise to the analyses of the fungal communities in the treated plots. Song noted that increasing crop yields could do more than simply add to the food supply. It could also lead to more efficient alternative energy production. “In a shift to more biofuel production, the Department of Energy requires you to grow biofuel crops that don’t compete with traditional crops,” he said. “If you can reduce crop loss before harvest, then you can produce both food and biofuel without compromising either.”

Managing Microbes in Brazil’s Agricultural South

BTI Director travels to Brazil to mentor students researching bioremediation of agriculture chemicals.

BY ALLISON KRONBERG

BTI Director Michael Sadowsky understands both French and Spanish, but hardly a word of Portuguese. Yet this summer he launched a two-year collaborative research initiative in Ponta Grossa, Brazil, as part of the Brazilian Government’s Science Without Borders Project.

Sponsored by Brazilian National Council for Scientific and Technological Development (CNPQ), Brazil’s equivalent of the National Science Foundation, the program allows Sadowsky to share his expertise in microbiology and bioremediation with colleagues and students in this Southern Brazilian industrial and agricultural center.

In Brazil, Sadowsky works alongside his long-time colleague Marcos Pileggi, a professor of biology and evolution at the Universidade Estadual de Ponta Grossa. Along with Pileggi’s students, the pair will conduct research on bacterial pesticide degradation that could help protect Brazil’s environment and save money for local farmers and pesticide manufacturers.

According to Sadowsky, Brazilian farmers receive concentrated chemicals from pesticide and herbicide companies, often in five-gallon buckets. Farmers then transfer the liquid to large tanks and add water to dilute the chemicals before spraying.

But not all of the pesticide is used and the toxic residue can’t be thrown away or dumped in the environment. Some manufactures provide a pick-up service for the remaining liquid, and store it in large tanks where it degrades over time. But if the biodegradation is incomplete, they burn it — and burning liquid is very expensive.

With Sadowsky’s help, Pileggi and his lab of 10 undergraduate and graduate students hope to identify bacteria that will naturally and efficiently degrade the concentrated liquid waste. During Sadowsky’s first 10-day trip, the group created a research plan and took initial steps toward isolating bacteria capable of degrading leftover pesticides and herbicides.

“Bacteria are the most versatile tool we have for degrading compounds in the environment,” Sadowsky said. “We are trying to find more environmentally friendly ways of doing things, and very often that involves old-fashioned microbiology.”

The team put the chemicals in a tank and added different types of bacteria to see which microbes would survive and grow using the pesticides and herbicides as a food source. The technique (called enrichment) was developed in the late 1800s and is still considered the most effective way to find bacteria that can breakdown chemical compounds.

Sadowsky, who also serves as co-Director of MnDRIVE’s microbial bioremediation initiative, began international scientific work in the 80s, and he has visited Brazil a few times before, but this is his first fully funded research trip abroad.

“Brazil is a good place to perform the research,” Sadowsky said, “because some of the herbicides and pesticides the lab is now studying have been banned in the United States.”

The seed for the collaboration was planted almost five years ago when Pileggi came to Minnesota to research pesticide degradation with Sadowsky’s lab. Now, upon Pillegi’s request, the two professors have swapped roles.

“This is a great experience for me,” Sadowsky said. “Hopefully we’ll develop some new technologies out of this research. But that’s going to take some time, and we’ll have to see if it really comes to fruition.”

Sadowsky’s trip has a strong educational focus as well, and supports Science Without Border’s goal of increasing the number of Brazilian Ph.D.’s  through international scientific research and collaboration.

“Mike is helping me organize my Environmental Microbiology Laboratory with more focus and efficiency,” Pileggi said. “He pushed us a lot, and we enjoyed it.”

Students from the Universidade Estadual de Ponta Grossa, can continue their training at institutions like the Federal University system, which grants Ph.D.’s.

Sadowsky will travel to Brazil six times over the next two years. Once the project is complete, he hopes to invite some of the Brazilian students to the United States where they can receive advanced training in new and emerging technologies.