January 28, 2021

Allison Coomber (North Carolina State University)

Evolution of the effectome of Phytophthora infestans on tomato

Fall 2020 Graduate Student Award in Pathogenic and Commensal Organisms


Late blight, the disease that damaged the potato crop during the Irish Potato Famine, is caused by Phytophthora infestans, a fungus-like organism. Despite changes in agriculture, late blight still infects fields across the globe, causing significant losses for farmers. Currently, late blight is managed with fungicides or resistant varieties. However, resistance does not usually last very long. Once a crop plant is made resistant, the pathogen evolves and adapts to the host resistance. When the pathogen adapts, it is able to overcome the resistance in the host and cause severe disease again. Obtaining durable resistance to late blight thus remains a goal.

Recently, disease samples were found in Western North Carolina that are able to infect even the most “resistant” tomato plants. This breakdown of resistance may make future outbreaks of the disease more severe. In this study, we will investigate how the pathogen was able to evolve and adapt to overcome the tomato resistance genes. We have pathogen isolates from host plants with a range of resistances. These isolates will be used to inoculate several host plants with different resistance genes. The infection will then be transmitted to a new generation of plants, allowing the disease to evolve in the laboratory. By comparing the genetic sequence of the pathogen at the start to the sequence after artificial evolution in the lab, we will elucidate how the genome is changing and glean insight into what might make resistance more durable.