Abstract
Ethylene evolution was induced in 03-treated tomato plants and activities of ACC synthase and ACC oxidase were suggested to be rate-limiting steps. We isolated cDNA fragements encoding ACC synthase (LEOSY 1 and LEOSY 2) and ACC oxidase (LEOOX 1 and LEOOX 2) from 03-treated tomato leaves. The sequences of LEOSY 1, LEOSY2 and LEOOX 1 were different from those of known ACC synthase and ACC oxidase. Furthermore, the transcripts encoding LEOSY 1 and LEOOX 1 considerably increased in O3-treated leaves. These results suggest that ethylene evolution enhanced by 03 treatment was mediated by LEOSY 1 and LEOOX 1 which were induced by O3 treatment.
