Fig. 6. Overexpression or RNAi knockdown of MdMYB8 (MD06G1217200) in apple calli (Malus domestica cv. ‘Orin’).

a The control (pBI101), MdMYB8-overexpressing (pBI101-MdMYB8), and MdMYB8-knockdown (pBI101-RNAi-MdMYB8) apple calli were observed in daylight and under UV light. Calli were stained with the flavonol-specific dye DPBA. b Contents of flavonoid compounds in MdMYB8 (MD06G1217200)-overexpressing ‘Orin’ apple calli and those subjected to RNAi. c, d qRT-PCR analysis of flavonoid biosynthetic genes in the MdMYB8 (MD06G1217200)-overexpressing ‘Orin’ apple calli and those subjected to RNAi. qRT-PCR and HPLC analyses were performed on three biological replicates. Error bars indicate the standard error of the mean ± SE of three replicate measurements. Different letters above the bars indicate significantly different values (P < 0.05), calculated using one-way analysis of variance (ANOVA) followed by Tukey’s multiple range test