Researchers Uncover Defense Dynamics of Potato Late Blight Pathogen

Phytophthora infestans, the pathogen that caused the Irish Potato Famine in the 1840s is still a major threat to potato and tomato crops worldwide. This pathogen can devastate entire fields, posing a constant threat to global food security. In a new study, researchers at the Boyce Thompson Institute (BTI) and Universidad de los Andes have discovered that P. infestans can develop a rapid, temporary resistance to the fungicide mefenoxam after a single, low-dose exposure.

This resistance is not a result of a permanent genetic mutation. Instead, it is a reversible epigenetic change, described as a "biological toggle switch." The pathogen can "flip on" this switch to survive when exposed to the fungicide and "flip off" to become sensitive again when the chemical threat is gone. This process is energy-intensive, which is likely why the pathogen only uses this defense mechanism when necessary. While the resistance allows the pathogen to survive, it does not increase its ability to reproduce.

The pathogen employs a defense mechanism known as pleiotropic drug resistance (PDR), which activates cellular pumps to eject the fungicide. However, this process requires significant energy, which likely explains why the pathogen readily abandons the resistance once it's no longer necessary. This discovery provides crucial insights into the pathogen's survival strategies and will help develop more effective, sustainable methods for managing this global crop threat.

For more details, read the article in BTI News.