• ethylene;
  • leaf damage;
  • transgenic plant.


Antisense DNA for an ozone-inducible 1-aminocyclopropane-1-carboxylate (ACC) synthase (EC; LE-ACS6) from tomato, under the control of the cauliflower mosaic virus 35S promoter, was introduced into tobacco to generate transgenic plants. Lower rates of ozone-induced ethylene production were observed in three of seven transgenic plants than in the wild-type plants. Ozone-induced visible damage was attenuated in these three lines, and the extent of damage was positively related to the level of ozone-induced ethylene production. In the most ozone-resistant line, ozone-induced accumulation of ACC and levels of transcripts for ozone-inducible endogenous ACC synthases were suppressed compared with those in wild-type plants, demonstrating that ozone-inducible ACC synthases have a key role in the expression of leaf damage by ozone exposure. No significant differences in growth and morphology were observed between transgenic and wild-type plants. Stomatal conductance of transgenic plants during ozone exposure was higher than that of wild-type plants. These findings indicate that the introduction of antisense DNA for an ozone-inducible ACC synthase can improve the ozone tolerance of plants without reducing their gas absorption and productivity.