Fig. 4: Expression analysis by RT-qPCR of ethylene biosynthesis genes in apple tissues subjected to sudden sun exposure.

Transcript levels of 1-aminocyclopropane-1-carboxylate synthase (MdACS) and 1-aminocyclopropane-1-carboxylate oxidase (MdACO) were analyzed after different times of sun exposure in the skin (a, c) and flesh (b, d) of Fuji apples and in the skin (e, g) and flesh (f, h) of Royal Gala apples. Non-Exp: nonexposed fruit; Exp: exposed fruit without sun damage; Sev: exposed fruit with severe sun damage. Data correspond to the mean ± SE of three biological replicates. Different letters indicate significant differences, with Non Exp fruit as the control (P < 0.05; two-way ANOVA)