[Production and releasing sites of superoxide anion in phytopathogenic bacteria].

Many phytopathogenic bacteria were founded to release the superoxide anion (O2-) by themselves from different sites and the production of O2- was related to the pathogenicity of strains. The presences of O2- in cytomembrane, cell wall and filtrate were confirmed by chemical method and electron spin resonance (ESR). The results show that filtrate may be the primary site of O2- production due to its higher O2- generating activity either in the presence or the absence of DDC. Additional lines of evidence further suggested a regulatory mechanism of O2- production in phytopathogenic bacteria.

[O2-* burst of tobacco leaves triggered by Erwinia carotovora subsp. carotovora inoculation].

O(-.)(2) production based on chemical method by Ecc-treated intact tobacco leaves was observed. It showed a long-lasting one-phase course beginning 1 h and ending 14 h after Erwinia carotovora subsp. carotovora (Ecc) was inoculated. In Ecc-treated leaves, O(-.)(2) production rate of 3 h is 2 times of 1 h, and of 10 h it remains 1.7 times. It decreases rapidly between 10 h and 14 h, at 14 h it falls to the level before inoculation. This is a completely different course from the widely accepted two-phase course obtained from suspension-cultured cells. Electron spin resonance (ESR) spectrum of O(-.)(2) produced by intact tobacco leaves after Ecc inoculation 2 h and 6 h was also observed, the amplitude of 6 h is larger than of 2 h in Ecc-treated group. In the control group, there is no difference between the amplitude of 2 h and 6 h. This indicated that O(-.)(2) amount of Ecc-treated group is higher than of the control group, which is the same result as obtained through chemical method. The ESR spectrum of O(-.)(2) produced by chloroplasts and mitochondria from tobacco leaves after 2 h and 6 h after Ecc inoculation were observed. In chloroplast experiment, the amplitude of 6 h was larger than of 2 h in Ecc-treated group while it was the same in the control group. ESR spectrum of O(-.)(2) produced by mitochondria was proved to be a same result after a careful comparison, in spite of a greater difference between 2 h and 6 h in control group than chloroplast experiment. The fact that spectra of these two organelles were both synchronous with that of intact leaves implied that these two organelles possibly participated in cellular O(-.)(2) burst. Chloroplasts in the dark showed no ESR spectrum 2 h and 6 h after Ecc inoculation in Ecc-treated group as well as in the control group, indicating that O(-.)(2) in the chloroplast probably originated from the photosynthetic electron transport process.