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Physiology and Biochemistry

Early Responses During Plant-Bacteria Interactions in Tobacco Cell Suspensions. C. Jacyn Baker, Microbiology and Plant Pathology Laboratory, United States Department of Agriculture, ARS, Beltsville, MD 20705; Nichole R. O’Neill(2), L. Dale Keppler(3), and Elizabeth W. Orlandi(4). (2)Germplasm Quality and Enhancement Laboratory, USDA, ARS, Beltsville, MD 20705; (3)(4)Microbiology and Plant Pathology Laboratory, United States Department of Agriculture, ARS, Beltsville, MD 20705. Phytopathology 81:1504-1507. Accepted for publication 24 July 1991. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1991. DOI: 10.1094/Phyto-81-1504.

Bacteria that induce a hypersensitive response in tobacco leaves initiate a net uptake of extracellular H⁺ and a net increase in extracellular K⁺ in tobacco suspension cells. Other studies have shown that these interactions also result in a transient increase in lipid peroxidation and O₂^– production. The relationships between these early plant responses were studied simultaneously using suspension-cultured tobacco cells and compatible, incompatible, and saprophytic bacteria. The bathing medium was monitored during a 6-h period for pH, conductivity, [K⁺], and luminol-dependent chemiluminescence. In all bacterial treatments, an immediate increase in chemiluminescence and pH occurred within 30 min after addition of the bacteria. After about 2 h a second increase in pH, conductivity, [K⁺], and chemiluminescence occurred with incompatible bacteria. The first response appears nonspecific, while the second response appears to depend on the host/pathogen incompatibility.