research team mentor

Principal Investigator
Rachel Penczykowski, PhD

Assistant Professor of Biology, Washington University in St. Louis
Research website:

Research focus for summer 2018

How does ecological context drive epidemiology and host-pathogen coevolution? This is a central question of disease ecology, and one that is critical for predicting and managing diseases of humans, wildlife, and plants. Our lab is addressing this question by studying common broadleaf weeds (Plantago species) and their powdery mildew pathogens along the entire Mississippi River. We are investigating how disease prevalence and the diversity of pathogen strains varies along this latitudinal gradient. We have collected seeds and pathogen strains from populations along this gradient, which allows us to test for patterns of host resistance and pathogen infectivity in the lab and through field experiments. In summer 2018, we plan to set up a common garden experiment at Tyson in which seeds from several populations are planted together, exposed to naturally occurring herbivores and pathogens, and sampled to quantify damage by herbivores and disease. Together with similar experiments performed at different latitudes, this experiment will shed light on the roles of host genotype and environmental conditions in driving disease.

In addition, we will census powdery mildew infection on Plantago along roadsides at Tyson, and establish a permanent research plot to be part of the international PlantPopNet network. This network uses replicated plots of Plantago to study fundamental questions about population ecology, including disease ecology.


Students will plant seeds and/or transplant seedlings of Plantago into a common garden at Tyson. They will also be involved in maintenance (e.g., watering and fertilizing) of the garden and collecting data on plant growth, flowering, damage by herbivores, and infection by powdery mildew or other plant pathogens.

Students will survey Plantago along roadsides and other open areas at Tyson. They will be trained in identifying the focal plant species and plant pathogen(s), systematically counting healthy and infected plants, and measuring key plant traits.

Students will also aid in the selection and set-up of a permanent research plot to be added to the international PlantPopNet network. This will involve measuring and tagging plants to be revisited yearly for several years.

research conditions

Students can expect to be in the field 70% of the time and lab 30% of the time. Lab work will include identifying plant pathogens under a dissecting microscope and performing DNA extractions of infected plant tissue for determining pathogen strain genotype.

Field conditions will be primarily in short vegetation in open habitats. Students will need to take precautions against ticks, mosquitoes, and sunburn.

Team structure and opportunities for independent research

This is the first summer of the Penczykowski Lab at WashU. Our lab group is currently small, and the PI will be directly involved with most of the work at Tyson this summer. We have a few undergraduate students working in the lab this academic year who may continue in the summer, and we hope to hire and train a lab technician this spring who would be a key member of the team. There are many opportunities for independent research in the group.