For the cloning of ACO (ACC-oxidase) gene, RT-PCR was carried out to amplify the nucleotides encoding conserved domains of ACO protein in carnation cv. Yellow Liberty. 563 bp of RCR product was subcloned, sequenced, and named ACO-1. The amino acid sequence of ACO-1 was same as ACO proteins in other carnation cultivars. Partial cloned ACO-1 was revealed to detect effectively variation in the amount of transcript of ACO in carnation cv. Pink Donor treated with chemicals influencing the ACO activity.