MOLECULAR STUDIES OF ACC SYNTHASE AND ACC OXIDASE GENES IN APPLE

The purpose of this work was to search for correlations between the rate of ethylene production during ripening of apple fruits and the molecular structure of the genes involved in its synthesis. To this end, the ethylene production of apple fruit, characterised by slow (‘Fuji’) or fast (‘Golden Delicious’) ripening, was estimated by gas chromotography. The cDNA sequences of the ACC synthase and ACC oxidase genes specific for ethylene production in fruits were retrieved from the EMBL data library and used to design specific DNA primers to be used for their PCR synthesis. With these tools, the genomic DNA of 12 Malus species and cultivars was analysed by PCR-RFLP. The amplified ACC synthase DNA fragments showed identical molecular weight in all assessed genotypes; on the other hand, the ACC oxidase amplification products showed different molecular weights and restriction patterns. In the latter case, the analysis of the restriction products showed evidence of the existence of at least two allelic forms of the gene. It is possible that allelic forms of ACC oxidase may correlate with the wide range of ethylene production during fruit ripening that occurs in different cultivars