Quantifying the Contribution to Virulence of Phytophthora infestans Effectors in Potato

Late blight in potato, caused by the oomycete Phytophthora infestans, is a devastating disease that significantly impacts potato production. For a proper understanding of disease development, it is important to understand the interaction between plant and pathogen at a molecular level. Like other pathogens, P. infestans secretes effector molecules, which can be recognized by receptors in the plant and trigger immunity. In addition, effectors from P. infestans have been identified to enhance disease development. Here, we describe an assay to investigate the role of effectors in virulence of P. infestans on potato. We combine agroinfiltration to transiently express effectors in potato with detached leaf assays to monitor disease development. This protocol makes it possible to conveniently quantify the effect of individual effectors on virulence of P. infestans. The identification of effectors with an important role in late blight development can help to design better strategies to control the disease.