Therefore, it seems that the effects of CA in inducing PAL but inhibiting POD activity may be widespread in dicots and monocots. Additionally, the results of our study indicates that CA treatment induced the activities of cinnamic acid-4-hydroxylase (C4H), another important enzyme in the early steps of phenylpropanoid metabolism, at the early stage of russet formation of ‘Golden Delicious’ apples (Fig. 5). Furthermore, the CA treatment was found to up-regulate the gene expressions of PAL, C4H, C4L (Fig. 7), CHS and CHI (Fig. 8)