Dual Transcriptomic and Metabolomic Analysis of Elicited Flax Sheds Light on the Kinetics of Immune Defense Activation Against the Biotrophic Pathogen .

Flax () grown under controlled conditions displayed genotype-dependent resistance to powdery mildew () following COS-OGA (comprising chitosan- and pectin-derived oligomers) elicitor application. The present study reveals a two-step immune response in plants preventively challenged with the elicitor: an initial, rapid response characterized by the transcription of defense genes whose protein products act in contact with or within the cell wall, where biotrophic pathogens initially thrive, followed by a prolonged activation of cell wall peroxidases and accumulation of secondary metabolites. Thus, dozens of genes encoding membrane receptors, pathogenesis-related proteins, and wall peroxidases were initially overexpressed.