VIEW ARTICLE

Relationship of Ammonia to Necrosis of Pepper Leaf Tissue During Colonization by Xanthomonas vesicatoria. R. E. Stall, Department of Plant Pathology and Department of Vegetable Crops, University of Florida, Gainesville 32601; C. B. Hall(2), and A. A. Cook(3). (2)(3)Department of Plant Pathology and Department of Vegetable Crops, University of Florida, Gainesville 32601. Phytopathology 62:882-886. Accepted for publication 14 February 1972. DOI: 10.1094/Phyto-62-882.

Ammonia accumulated in nutrient broth cultures during growth of Xanthomonas vesicatoria. Ammonia also accumulated in inoculated leaves of a pepper cultivar that was susceptible to a strain of X. vesicatoria, but did not in inoculated leaves of a pepper breeding line that was hypersensitive to the bacterium. Both types of pepper leaves were damaged by amounts of NH₃, generated from NH₄ Cl, that were found in inoculated susceptible leaves after necrosis. Sensitivity of both types of pepper leaves to NH₃ from NH₄ Cl was similar, also. With inoculated susceptible leaves, a positive correlation was obtained between NH₃ accumulation and electrolyte leakage when plants received nitrogen fertilization. Necrosis occurred without significant increases in NH₃ in N-deficient leaves inoculated with the bacterium. Thus, ammonia accumulation was not necessary for necrosis of hypersensitive, or susceptible, leaf tissue following bacterial inoculation, and probably occurred after leakage of nitrogenous materials from the protoplasm.