RNA-seq analysis of chitin-triggered transcriptional reprogramming in the Arabidopsis mapkkk5 mutant

Perception of microbe-associated molecular patterns by host cell-surface pattern recognition receptors triggers a series of immune responses such as activation of mitogen-activated protein kinase (MAPK) cascades. In Arabidopsis thaliana, the receptor-like cytoplasmic kinase PBL27 interacts with the chitin receptor CERK1 and regulates chitin-induced MAPK activation. We found that the MAPK kinase kinase MAPKKK5 connects PBL27 to the downstream MAPK Kinases (MKK4/5) and MAPKs (MPK3/6). RNA-seq analysis using the mapkkk5 mutant indicated that MAPKKK5 plays important roles in chitin-induced transcriptional reprogramming. As far as we are aware, this is the first report pointing to the significance of a complete MAPK cascade in defense-associated transcriptional reprogramming in plants. Overall design: Arabidopsis Col-0 and mapkkk5-1 were treated with mock or chitin (40mM) for 3 hours. Three independent experiments were performed.