Figure 10.

Effects of ethylene and salicylate on O₃-induced cell death in tobacco cell cultures. Effects of two phytohormones, ethylene (C₂H₄, 100 ppm, 10 min prior to the O₃ pulses) and sodium salicylate (NaSA, 1 mM) in Bel-W3 (A) and Bel-B (B) cells. Ethylene pretreatment was carried out by injecting the gaseous ethylene into 50-ml gas-tight tube with a silicone rubber port (containing 10 ml of cell suspension) through the needle of a syringe. The cells were incubated with 100 ppm ethylene for 10 min with continuous shaking. Sodium salicylate was simply added prior to the O₃ pulse. Then Bel-W3 and Bel-B cells were exposed to ozonized air for 0, 7, 15 min. For development of cell death, cells were incubated for further 2 h after O₃ exposure. Four randomly chosen digital images of different portion of each sample under microscopes were acquired and stained cells were counted. Thus, each data point reflects the mean and S.E. (vertical bars, n = 4). Typical data from duplicate experiments are shown.