title: Alternative oxidase impacts the plant response to biotic stress by influencing the mitochondrial generation of reactive oxygen species.
abstract: Previously, we showed that inoculation of tobacco with Pseudomonas syringae incompatible pv. maculicola results in a rapid and persistent burst of superoxide (O(2)             (-) ) from mitochondria, no change in amount of mitochondrial alternative oxidase (AOX) and induction of the hypersensitive response (HR). However, inoculation with incompatible pv. phaseolicola resulted in increased AOX, no O(2)             (-)  burst and no HR. Here, we show that in transgenic plants unable to induce AOX in response to pv. phaseolicola, there is now a strong mitochondrial O(2)             (-)  burst, similar to that normally seen only with pv. maculicola. This interaction did not however result in a HR. This indicates that AOX amount is a key determinant of the mitochondrial O(2)             (-)  burst but also that the burst itself is not sufficient to induce the HR. Surprisingly, the O(2)             (-)  burst normally seen towards pv. maculicola is delayed in plants lacking AOX. This delay is associated with a delayed HR, suggesting that the burst does promote the HR. A O(2)             (-)  burst can also be induced by the complex III inhibitor antimycin A (AA), but is again delayed in plants lacking AOX. The similar mitochondrial response induced by pv. maculicola and AA suggests that electron transport is a target during HR-inducing biotic interactions.
authors.affiliation: Departments of Biological Sciences and Cell and Systems Biology, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4.
authors.forename: Marina
authors.initials: M
authors.lastname: Cvetkovska
authors.forename: Greg C
authors.initials: GC
authors.lastname: Vanlerberghe
mesh_terms: D000968:Antimycin A; D054884:Host-Pathogen Interactions; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D010935:Plant Diseases; D010940:Plant Proteins / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014026:Nicotiana / Q000201:enzymology* / Q000382:microbiology; D000099188:Alternative Oxidase
chemical_list: D000968:Antimycin A; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D000099188:Alternative Oxidase