COLD-INDUCED ACCUMULATION OF 1-AMINOCYCLOPROPANE 1-CARBOXYLATE OXIDASE PROTEIN IN GRANNY-SMITH APPLES

Preclimacteric Granny Smith apple (Malus domestica Borkh.) fruits exhibited a sharp increase in ethylene production after 5 days in the cold (4 degrees C), while in the absence of chilling (17 degrees C) ethylene production started to increase only at 35 days. Antibodies raised against a recombinant tomato 1-aminocyclopropane 1-carboxylate oxidase - the enzyme catalyzing the conversion of ACC into C2H4 - were used to demonstrate an accumulation of ACC oxidase protein in fruits stored at 4 degrees C which paralleled the increase in ethylene production. Two-dimensional gel electrophoresis indicated that the protein corresponded to one polypeptide species only which was identical in both chilled and non-chilled fruits. These results therefore indicate that ACC oxidase, in addition to ACC synthase, is induced during chilling of pre-climacteric Granny Smith apples and accumulates before any transfer of the fruit to warmer temperatures.