Wound and ethylene induction of the ACC oxidase melon gene CM-ACO1 occurs via two direct and independent transduction pathways.

The enzyme ACC oxidase catalyses the last step of ethylene biosynthesis in plants. Expression of the melon ACC oxidase gene, CM-ACO1, is rapidly induced (within 10 min) by ethylene treatment or upon wounding in leaves. The inhibitor of ethylene action, 1-methylcyclopropene (1-MCP), inhibited the accumulation of ethylene-induced CM-ACO1 mRNA transcripts, while wound-induced expression of the gene was not affected. The 5'-untranslated region of the CM-ACO1 gene was fused to the beta-glucuronidase (GUS) reporter gene and the corresponding transgenic tobacco plants were analysed. Two separate regions of the CM-ACO1 promoter activated GUS expression in response to ethylene treatment and wounding. These results suggest that induction of CM-ACO1 gene expression occurs via two separate signal transduction pathways in response to wounding and ethylene treatment.