title: Roles for mannitol and mannitol dehydrogenase in active oxygen-mediated plant defense.
abstract: Reactive oxygen species (ROS) are both signal molecules and direct participants in plant defense against pathogens. Many fungi synthesize mannitol, a potent quencher of ROS, and there is growing evidence that at least some phytopathogenic fungi use mannitol to suppress ROS-mediated plant defenses. Here we show induction of mannitol production and secretion in the phytopathogenic fungus Alternaria alternata in the presence of host-plant extracts. Conversely, we show that the catabolic enzyme mannitol dehydrogenase is induced in a non-mannitol-producing plant in response to both fungal infection and specific inducers of plant defense responses. This provides a mechanism whereby the plant can counteract fungal suppression of ROS-mediated defenses by catabolizing mannitol of fungal origin.
authors.affiliation: Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7609, USA.
authors.forename: D B
authors.initials: DB
authors.lastname: Jennings
authors.forename: M
authors.initials: M
authors.lastname: Ehrenshaft
authors.forename: D M
authors.initials: DM
authors.lastname: Pharr
authors.forename: J D
authors.initials: JD
authors.lastname: Williamson