Molecular and cellular analysis of the role of RBOH NADPH oxidases in barley stress response
In plant-microbe interactions, the apoplastic oxidative burst is one of the earliest events in response to elicitor perception or fungal cell wall penetration. Reactive oxygen species (ROS) are involved in defense gene expression, phytoalexin production, and the regulation of hypersensitive cell death reactions and, hence, play a central role in the interaction of plants with microbial pathogens. NADPH oxidases (Respiratory burst oxidase homologues, RBOHs) appear as key proteins in pathogenesis-related ROS production. RBOHs are plasma membrane resident proteins that produce extracellular O2.-, which is subsequently converted to H2O2. Besides its function as a signalling molecule, H2O2 is required for peroxidase-dependent lignification and for protein cross-linking in the cell wall. Both functions can be attributed to the basal resistance response. However, ROS have also functions in fungal pathogenicity and susceptibility to diseases. The role of RBOH-type oxidases in the pathogen response of barley is just beginning to be understood for single RBOH family members (Trujillo et al. 2006; Proels et al. 2010; Torres et al. 2017). Therefore, we aim at a deep analysis of the function of RBOHs in signalling and basal resistance to powdery mildew fungi and other leaf pathogens. To this end we apply genetic and cell biological approaches for understanding of the function of RBOH genes in compatibility with diverse fungal microbes, in non-specific elicitor signal transduction and in cell wall rigidity. Additionally, we investigate RBOH-functions in reprogramming of the host metabolome and transcriptome under biotic and abiotic stress.