Metabolic and transcriptional response of Arabidopsis thaliana wildtype and mutants to Phytophtora infestans

The oomycete P. infestans is the causal agent of late blight, the most devastating potato disease. In contrast to potato, A. thaliana is able to successfully prevent colonization of the pathogen due to a multi-layered nonhost resistance. Several mutants have been isolated which are impaired in penetration resistance. A mutation in the gene PEN2, which encodes for an enzyme involved in indole glucosinolate metabolism, results in the loss of penetration resistance against P. infestans. Despite its ability to penetrate epidermal cells of pen2 mutant plants, P. infestans is still not able to colonize these plants. Additional mutants were isolated which show enhanced defense responses upon infection with P. infestans: pen2erp1 and pen2erp2, and backcrossed mutants erp140 and erp2D. We used 6 different plant lines, the wildtype-like gl1, and the five different mutants (pen2, pen2erp1, pen2erp2, erp2D, erp140). The plants were either infected with P. infestans spores or treated with water as control, and harvested 6 h and 12 h after treatment. The experiment was repeated 3 times with different P. infestans cultures, resulting in biological triplicates, for an overall of 6 x 2 x 2 x 3 = 72 samples.