Characterization of the 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase multigene family of Malus domestica Borkh

The expression of two ACO genes, in addition to the well characterized MD-ACO1, and their protein products is reported. While MD-ACO1 is expressed in mature fruit, the other ACC oxidase genes are also expressed in fruit and in leaf tissues and the significance for ethylene production in apple is discussed.