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Role of Bacterial Immobilization in Race-Specific Resistance of Soybean to Pseudomonas syringae pv. glycinea. W. F. Fett, Eastern Regional Research Cetner, USDA, ARS, Philadelphia, PA 19118; S. B. Jones, Eastern Regional Research Cetner, USDA, ARS, Philadelphia, PA 19118. Phytopathology 72:488-492. Accepted for publication 13 July 1981. 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, 1982. DOI: 10.1094/Phyto-72-488.

Electron micrographs of leaf intercellular spaces of the soybean (Glycine max) differential cultivars Flambeau and Harosoy spray inoculated with Pseudomonas syringae pv. glycinea showed bacterial cells of both homologous and heterologous strains occasionally enveloped by electron-dense material at 4 and 24 hr after inoculation. However, there was no evidence that this was an active or specific host response. Structures similar to those enveloping bacteria were found cross-bridging adjacent leaf mesophyll cells at cell junctions in water-infiltrated and, to a lesser extent, uninfiltrated leaf tissue. Often, a distinct layer of fibrillar material was found in contact with plant cell walls and appeared contiguous with structures enveloping bacteria or with cross-bridges in uninoculated leaf tissue. Bacterial envelopment was not seen in several heterologous P. syringae pv. glycinea-soybean combinations, even though a typical hypersensitive response was induced, indicating that bacterial attachment per se is not a prerequisite for induction of the hypersensitive response in soybean. From experiments with rifampicin, induction time for the hypersensitive response was determined to be between 2 and 4 hr.

Additional keywords: bacterial blight.