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The Hypersensitive Reaction in Tobacco Leaf Tissue infiltrated with Pseudomonas pisi 4. Scanning Electron Microscope Studies on fractured Leaf Tissue
Author(s) -
Sigee D. C.,
AlIssa A. N.
Publication year - 1983
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/j.1439-0434.1983.tb00022.x
Subject(s) - vacuole , desiccation , biology , bacteria , cell wall , chloroplast , electron microscope , scanning electron microscope , botany , infiltration (hvac) , biophysics , cell , bacterial cell structure , microbiology and biotechnology , cytoplasm , biochemistry , materials science , physics , gene , optics , composite material , genetics
Leaves of tobacco infiltrated with Pseudomonas pisi were fractured at various times during the course of the hypersensitive reaction to expose cell surfaces within the tissue and mesophyll cell contents. Scanning electron microscopy of cross‐fractured mesophyll cells did not reveal any gross change in internal structure during the reaction induction period (0—2 h), but breakdown of tonoplast and collapse of chloroplasts commenced at about 5 h, during the latent period. Death of the mesophyll cells was followed by condensation of cell contents, and pronounced stretching of cell walls, due to desiccation and shrinkage.Between 0—6 h after infiltration, bacteria were largely confined to cell junctions, frequently within droplets. With collapse of the host cells and release of cell fluid, numbers of bacteria increased considerably (many dividing cells), and there was a shift of bacterial distribution to the whole mesophyll cell surface. The progressive desiccation that occurred between 10—20 h prevented further bacterial increase, but numbers of bacteria remained stable. Death of bacteria commenced at about 15 h, and was accompanied by the formation of numerous surface protrusions, which detached and deposited over the whole mesophyll surface.