ELECTRON-MICROSCOPE STUDIES ON PSEUDOMONAS-SYRINGAE PV PHASEOLICOLA ISOLATED FROM INOCULATED TOBACCO-LEAVES - CHANGES IN FLAGELLATION, BIOMASS AND ELEMENTAL COMPOSITION DURING THE HYPERSENSITIVE REACTION

Cells of Pseudomonas syringae pv. phaseolicola were infiltrated into tobacco leaves. recovered from tissue macerates at various time intervals during the course of the hypersensitive reaction, then investigated by analytical electron microscopy to determine changes in flagellation, cell size/biomass and elemental composition. In this interaction, the rapid fall in viable count was paralleled by an immediate and progressive decrease in mean cell biomass and a delayed decrease in mean cell size. The percentage occurrence of flagella also showed a sharp fall, suggesting a marked inhibition of bacterial motility. X-ray microanalysis of individual cells in air-dried preparations revealed the routine presence of detectable levels of P, K and Ca throughout the time course. Although significant changes in mean mass fractions did occur, the elemental composition of bacterial cells remained relatively stable throughout. The maintenance of substantial levels of K during the hypersensitive reaction suggests that direct damage to bacterial cells, with resulting ion leakage, does not occur.