MAPK signaling cascades and transcriptional reprogramming in plant-pathogen interactions

Abstract

In plants, innate immunity is triggered through pattern recognition receptors (PRRs) in response to microbe-associated molecular patterns (MAMPs) to provide the first line of inducible defense. Plant receptor protein kinases (RPKs) represent the main plasma membrane PRRs perceiving diverse MAMPs. RPKs trigger mitogen-activated protein kinase (MAPK) module which is one of the earliest signaling events after plant sensing of the invading pathogen as they link the perception of external stimuli to cellular responses. MAPK signaling networks serve specific and overlapping roles in controlling the activities and synthesis of a plethora of transcription factors (TFs), enzymes, hormones, peptides, and antimicrobial chemicals, contributing to resistance against bacteria, oomycetes, and fungi. Transcriptional reprogramming has been carried out by one of the most studied WRKY family of transcription factors. Recently, genetic evidence directly proved its significance as positive and negative regulators of disease resistance. WRKY genes were shown to be functionally connected forming a transcriptional network composed of positive and negative feedback loops and feed-forward modules. Within a web of partially redundant elements, some WRKY factors hold central positions mediating fast and efficient activation of defense programs.