St. Louis is a plant science powerhouse, but outside the neatly tended rows of crops and gleaming greenhouses sits another treasure trove of biological data: The wild plants tucked into yards, sidewalk cracks, ditches and fields have much to reveal. WashU's plant scientists are also among the most skilled in the country at teasing out their secrets.
"Wild plants and their pathogens are important on their own because plants form the foundation of ecosystems," said Rachel Penczykowski, an associate professor of biology in WashU Art & Sciences. "They are also ideal systems for testing fundamental questions about disease, and there's a lot of applicability to improving crops."
Penczykowski's lab studies plant-pathogen interactions across geographic regions and climate zones. The scientists are exploring how environmental variation shapes infection risk, transmission and evolutionary change. What they learn in that lab can be applied to many other fields of science: crop and agricultural research, disease ecology and ecosystem science, just for starters. Penczykowski and a small team of collaborators recently were invited to compile a special issue on the topic of wild plant diseases, now published in Philosophical Transactions of the Royal Society B.
Studying wild plants allows for insights into possible adaptations to disease that no human-designed systems could provide. For instance, in the special issue, one of the studies looks at populations of fungal pathogens in wild tomato hosts.
This research is applicable to human problems on three levels. First, it contributes to a basic understanding of how different types of diseases affect plants. Second, this research spotlights how plants evolve defenses to pathogens and how pathogens, in turn, evolve to overcome those defenses. Finally, studying wild plant pathogen systems could yield answers when those pathogens hit crops. Understanding how plants and pathogens evolve in response to each other—and to the environmental factors that drive disease—can help humans be much better prepared for environmental threats.
In the broader field of disease ecology, there are fundamental questions about why big epidemics appear in certain circumstances, what to expect in the evolution of pathogens and how pathogens move between natural and human-managed systems. Wild plant research can help answer those questions, Penczykowski said.
"What we learn from wild plant-pathogen interactions can inform more sustainable management of crop diseases," she said.
In her disease ecology class at WashU, Penczykowski tasked her students with delving into an unexplored topic of plant pathology. That class project turned into a meta-analysis in the special issue: "Impacts of urbanization on pathogens and pests of wild and cultivated plants," led by postdoctoral researcher Kaylee Arnold.
The work of keeping track of participating students and researchers was a learning experience for Arnold, who joined Penczykowski's lab from a disease ecology background.
"Because it was a systematic literature review, it was a lot of work," Arnold said. Participating students and scholars initially searched thousands of abstracts, pulling every paper in English they could find about wild plant science. This enabled them to see where there are gaps in the research.
Penczykowski also authored the issue's introduction, along with an article on her new research on soil microbe-plant feedback mechanisms.
Plants accumulate species-specific microbes in their soil, she said. Plants are surrounded by a unique community that includes friendly microbes along with a preponderance of species-specific pathogens. The pathogens limit how much of the same plant can accumulate in one spot.
"This is a way to maintain biodiversity in natural ecosystems. If every plant is limited by its own set of pathogens, you get greater diversity of plants," Penczykowski said.
Wanting to further probe this feedback mechanism, her team added additional stressors to the plants and found strong evidence that this feedback mechanism was at work.
Wild plant disease scientists around the world comprise a relatively small research community, and the various environmental settings of their diverse study organisms allow for much creativity and innovation in the field.
"There have been many important discoveries in wild plant systems, and there is a lot of room for discovering new things," Penczykowski said. "They're such exciting study systems."
Publication details
Special issue: Wild plant pathosystems
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Citation: Understanding how wild plants handle shifting disease threats, conditions (2026, July 20) retrieved 20 July 2026 from https://phys.org/news/2026-07-wild-shifting-disease-threats-conditions.html
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