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Title: OXYGEN METABOLISM IN PLANT/BACTERIA INTERACTIONS: PSEUDO-OXIDASE ACTIVITY OF PEROXIDASE

Author
item Baker, Con
item Deahl, Kenneth
item DOMEK, JOHN - 1275 45 00

Submitted to: Biochemical and Biophysical Research Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: This paper presents evidence of biochemical pathways in which oxygen is metabolized in plants. One of the first plant responses to pathogens is the production of active oxygen somewhat similar to the animal response to pathogens. This occurs well before symptoms can be observed and therefore can potentilly be exploited to help make plants more resistant to pathogens through transgenic plants which modulate this response. A key hurdle is the lack of understanding oxygen metabolism within the plant. This manuscript provides evidence of important chemical mechanisms involving peroxidase and its ability to carry out multiple functions in oxygen metabolism which need to be considered. This study should be of interest to researchers in the area of plant/pathogen interactions and active oxygen production in plants.

Technical Abstract: The production of active oxygen (AO) during the recognition phase of plant/pathogen interactions has become a topic of interest in recent years. Many studies have suggested that membrane bound oxidases, similar to those found in leukocytes, are responsible for this AO burst. However, much of this evidence is based on in vitro studies in which exogenous NAD(P)H is added. The inhibition of the AO generation by DPI, an NADH oxidase inhibitor, is considered sufficient evidence to prove the source is the leukocyte-like oxidase. DPI has never been tested for its effects on other mechanisms in plants. Here we demonstrate that it can have a significant effect on peroxidases which are ubiquitous in plant cell organelles and walls. Depending on the timing of addition, DPI in the presence of peroxidase and exogenous NADH can initially cause the uptake of dissolved oxygen and thereby inhibit further production of AO. A recent model is modified to explain the pseudo-oxidase mechanism observed.