VIEW ARTICLE

Effect of Bacterial Infiltration on Photosynthesis of Bean Leaves. Andrew C. Magyarosy, Former Research Assistant, Departments of Plant Pathology and Cell Physiology, University of California, Berkeley 94720, Present address of senior author: United States Department of Agriculture, Salinas, California 93901; Bob B. Buchanan, Professor, Departments of Plant Pathology and Cell Physiology, University of California, Berkeley 94720. Phytopathology 65:777-780. Accepted for publication 20 February 1975. DOI: 10.1094/Phyto-65-777.

Bean leaves were infiltrated with a suspension (10⁹ cells/ml) of Pseudomonas phaseolicola, a virulent pathogenic bacterium (compatible combination), Pseudomonas fluorescens, a nonpathogenic or saprophytic bacterium, or with distilled water (control treatment). A loss of turgor was observed 8-10 hours after infiltration with the pathogen, analogous to the sequence of events reported for incompatible combinations (hypersensitivity). Changes in capacity for photosynthetic ¹⁴CO₂ assimilation and in chloroplast ultrastructure were monitored as a function of time after infiltration. The results indicate that (i) the pathogen causes a progressive decrease in the rate of photosynthesis that is followed by destruction of chloroplast membranes; (ii) the saprophyte causes a sharp transitory reduction in the rate of photosynthesis that is not associated with a structural change in chloroplasts; (iii) neither the pathogen nor the saprophyte alters photosynthetic products in leaves.