The former two genes are involved in the total secondary metabolism, and the latter three genes are involved in flavonoid biosynthesis and chlorogenic acid biosynthesis (Fig. 10). This may explain the transient accumulation of total flavonoids and endogenous chlorogenic acid in apple peels during the early stage of fruit development (Figs. 1 and 3). On the other hand, the expressions of the genes involved in lignin biosynthesis such as CAD, POD and PPO were found to be inhibited by the CA treatment (Fig. 9). As a result, the lignin accumulation was inhibited in ‘Golden Delicious’ apple peels after CA treatment (Fig. 4) when the fruit russet formation was prevented (Fig. 2)