Role of reactive oxygen species (ROS) in MAPK-mediated chemotropism and infectious growth of the plant pathogenic fungus Fusarium oxysporum

• Applicant: Dr. Daniela Elisabeth Nordzieke
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms ; General Genetics and Functional Genome Biology
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280327700

Chemotropism, the directed growth towards a chemical gradient, governs essential processes in fungi such as nutrient acquisition, sexual or asexual fusion and host infection. The nature of the chemoattractant molecules, as well as the chemotropic receptors and downstream signaling pathways are largely unknown. The host group at University of Córdoba has developed a method to quantitatively measure directed hyphal growth in the fungal plant pathogen Fusarium oxysporum. Genetic dissection of the chemotropic mechanism led to the identification of a mitogen-activated protein kinase (MAPK), Mpk1, as an essential component in the chemotropic response of F. oxysporum to host plant signals. Moreover, the major chemoattractant in root exudates was identified as a plant-secreted peroxidase, suggesting a role of reactive oxygen species (ROS) in MAPK-mediated chemotropic signaling. Here we propose to 1) study the role of the ROS-generating enzymes NADPH oxidases (Nox) in regulation of MAPK signaling and chemotropic growth, by determining MAPK phosphorylation status and chemotropic response in F. oxysporum nox deletion mutants and 2) to identify fungal target proteins that are modified by the ROS-dependent activity of the peroxidase, using cysteine trapping in sulfenic acid state and site-directed mutagenesis. We anticipate that the results will uncover novel molecular links and downstream targets of ROS and MAPK signaling in fundamental processes guiding fungal pathogenicity. This knowledge will be of interest for the development of new anti-fungal drugs. Overall, this project combines the experiences of the applicant and the host institute regarding ROS signaling in fungi and chemotropic growth, respectively. Further, it allows the applicant to work on a cutting-edge research topic in an internationally recognized research group providing her with optimal preparation to undertake innovative research in Germany in the upcoming years.

• DFG Programme: Research Fellowships
• International Connection: Spain
• Host: Professor Antonio Di Pietro, Ph.D.