Molecular cloning and expression of a cDNA encoding 1-aminocyclopropane-1-carboxylate (ACC) oxidase from apricot fruit (Prunus armeniaca)

Little is known on gene expression during ripening of apricot fruit (Prunus armeniaca cv. Bergeron), in particular for the enzymes involved in ethylen e biosynthesis. ACC oxidase (EC 1.4.3) catalyses the last step of the ethyl ene biosynthesis pathway in higher plants. Based on sequence conservation o f ACC oxidases, a reverse transcriptase-polymerase chain reaction (RT-PCR) experiment was carried out to synthesize a homologous ACC oxidase probe fro m apricot fruit. This probe was further used to isolate a full length ACC o xidase cDNA, Pa-ACO, from a ripe fruit cDNA library. Pa-ACO is 1 236 bp lon g and contains a single open reading frame encoding a mature peptide of 319 amino acids with a calculated molecular mass of 36.17 kDa and a pI of 5.07 . Immunoblot analysis allowed us to associate a 40 kDa protein to apricot f ruit ACC oxidase. Pa-ACO belongs to a multi-gene family, is fruit specific and is transcriptionally regulated during ripening of apricot fruit.