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Title: NITRIC OXIDE'S ROLE IN COMMON SCAB OF POTATO: PHYTOTOXIN BIOSYNTHESIS AND WHAT ELSE?

Author
item WACH, M - USDA-APHIS, MD
item JOHNSON, E - CORNELL UNIVERSITY
item Gibson, Donna
item LORIA, R - CORNELL UNIVERSITY

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2004
Publication Date: 7/30/2004
Citation: Wach, M.J., Johnson, E.G., Gibson, D.M., Loria, R. 2004. Nitric oxide's role in common scab of potato: phytotoxin biosynthesis and what else? [abstract]. American Phytopathological Society Annual Meeting. 94:S106

Interpretive Summary:

Technical Abstract: The thaxtomin family of phytotoxins are required by pathogenic Streptomyces species to cause common scab of potato. A gene encoding a nitric oxide synthase (NOS) is essential for normal levels of thaxtomin production. Evidence for the involvement of the S. turgidiscabies NOS (stNOS) in the biosynthesis of thaxtomin A (ThxA) supports a direct role for nitric oxide (NO) in the formation of the nitroindole moiety of ThxA. Streptomyces turgidiscabies was grown in the presence of a NO scavenger (CPTIO) to determine its effect on ThxA production. CPTIO reduced ThxA production without affecting bacterial growth. A strain of S. turgidiscabies from which the stnos has been deleted was grown in the presence of three NO donors (DEANO, SIN, and SNAP), and all three partially restored ThxA production. These results indicate an unexpected uncoupling of NO production and ThxA biosynthesis and suggest that the highly reactive and diffusible NO radical is present intra- and extracellularly. If so, this raises questions about whether NO derived from stNOS affects host-pathogen interactions. The presence and function of free NO in pathogenic streptomycetes are under investigation.