Nonhost resistance of Arabidopsis thaliana to Phytophthora infestans

Arabidopsis thaliana is able to successfully prevent infection and colonization by Phytophthora infestans, the causal agent of late blight disease of potato. This nonhost resistance is durable and based on several layers of defense. Pre-invasion resistance is the first layer and involves the activity of the myrosinase PEN2 which produces indole compounds from indole glucosinolates. Successful penetration of pen2 mutant plants by P. infestans leads to enhanced defense responses. To identify additional genes required for nonhost resistance, preferably at the post-invasion level, the progeny of mutagenized seeds of the pen2 mutant was screened for alterations in their response to P. infestans infection. Fourteen mutants with enhanced responses were isolated. The identification of the affected genes by map-based cloning and whole genome sequencing as well as the subsequent molecular analysis of the encoded proteins will provide insight into the mechanisms of successful defense against P. infestans.