NoxA activation by the small GTPase RacA is required to maintain a mutualistic symbiotic association between Epichloë festucae and perennial ryegrass
- 21 April 2008
- journal article
- Published by Wiley in Molecular Microbiology
- Vol. 68 (5), 1165-1178
- https://doi.org/10.1111/j.1365-2958.2008.06217.x
Abstract
Small GTPases of the Rac group play a key regulatory role in NADPH oxidase catalysed production of reactive oxygen species (ROS) in mammals and plants, but very little evidence is available for a corresponding role in fungi. We recently showed that ROS produced by a specific fungal NADPH oxidase isoform, NoxA, are crucial in regulating hyphal morphogenesis and growth in the mutualistic symbiotic interaction between Epichloë festucae and perennial ryegrass. We demonstrate here that E. festucae RacA is required for NoxA activation and regulated production of ROS to maintain a symbiotic interaction. Deletion of racA resulted in decreased ROS production, reduction of radial growth and hyper-branching of the hyphae in culture. In contrast, in planta the racA mutant showed extensive colonization of the host plant, resulting in stunting and precocious senescence of the host plants. Strains expressing a dominant active (DA) allele of RacA had increased ROS production, increased aerial hyphae and reduced radial growth. These results demonstrate that RacA plays a crucial role in regulating ROS production by NoxA, in order to control hyphal morphogenesis and growth of the endophyte in planta.Keywords
This publication has 44 references indexed in Scilit:
- Regulation of hyphal morphogenesis by cdc42 and rac1 homologues in Aspergillus nidulansMolecular Microbiology, 2007
- Fungal Endophyte Production of Reactive Oxygen Species is Critical for Maintaining the Mutualistic Symbiotic Interaction BetweenEpichloë festucaeand Perennial RyegrassPlant Signaling & Behavior, 2007
- Central Roles of Small GTPases in the Development of Cell Polarity in Yeast and BeyondMicrobiology and Molecular Biology Reviews, 2007
- A p67Phox-Like Regulator Is Recruited to Control Hyphal Branching in a Fungal–Grass Mutualistic SymbiosisPlant Cell, 2006
- Rac1 and Cdc42 regulate hyphal growth and cytokinesis in the dimorphic fungus Ustilago maydisMolecular Microbiology, 2005
- Molecular cloning and genetic analysis of a symbiosis-expressed gene cluster for lolitrem biosynthesis from a mutualistic endophyte of perennial ryegrassMolecular Genetics and Genomics, 2005
- Dominant active Rac and dominant negative Rac revert the dominant active Ras phenotype in Colletotrichum trifolii by distinct signalling pathwaysMolecular Microbiology, 2004
- Microscopic detection of reactive oxygen species generation in the compatible and incompatible interactions of Alternaria alternata Japanese pear pathotype and host plantsJournal of General Plant Pathology, 2003
- Growth of Epichloë / Neotyphodium and p-endophytes in leaves of Lolium and Festuca grassesMycological Research, 2002
- The GTPase superfamily: conserved structure and molecular mechanismNature, 1991