title: Functional analysis of a fungal endophyte stress-activated MAP kinase.
abstract: The ability of fungi to sense and respond rapidly to environmental stress is crucial for their survival in the wild. One of the most important pathways involved in this response is the stress-activated MAP (mitogen-activated protein) kinase pathway. We report here on the isolation of the stress-activated MAP kinase, sakA, from the fungal endophyte Epichloë festucae. Complementation of the stress sensitivity and cell cycle defects of an Schizosaccharomyces pombe sty1Delta mutant with sakA confirmed it encodes a functional MAP kinase. Analysis of an E. festucae DeltasakA mutant revealed sakA is essential for growth under conditions of temperature and osmotic stress in culture, and for sensitivity to the fungicide fludioxonil. However, the DeltasakA mutant shows no increased sensitivity to hydrogen peroxide. Given sakA can rescue the sty1Delta mutant from sensitivity to oxidative stress, SakA has the potential to sense and transduce oxidative stress signals. The DeltasakA mutant is also defective in conidia formation, suggesting a role for SakA in asexual development of E. festucae. The detection of elevated hydrogen peroxide production in the DeltasakA mutant suggests there may be a link between MAP kinase and ROS (reactive oxygen species) signalling pathways in E. festucae.
authors.affiliation: Institute of Molecular BioSciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand.
authors.forename: Carla J
authors.initials: CJ
authors.lastname: Eaton
authors.forename: Isabelle
authors.initials: I
authors.lastname: Jourdain
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Foster
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Hyams
authors.forename: Barry
authors.initials: B
authors.lastname: Scott
mesh_terms: D015153:Blotting, Western; D002453:Cell Cycle; D002467:Cell Nucleus / Q000378:metabolism; D025141:Drug Resistance, Fungal; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D031751:Festuca / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005659:Fungicides, Industrial / Q000494:pharmacology; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009997:Osmotic Pressure; D018384:Oxidative Stress; D010957:Plasmids; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D005656:Fungal Proteins; D005659:Fungicides, Industrial; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D020928:Mitogen-Activated Protein Kinases