Roles for mannitol and mannitol dehydrogenase in active oxygen-mediated plant defense.
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.
Jennings
D B
DB
Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7609, USA.
Ehrenshaft
M
M
Pharr
D M
DM
Williamson
J D
JD