Comparison among ‘Benitaka’ grape, ABA-treated ‘Benitaka’, and its deeper-colored bud mutation revealed the coloring mechanisms on grapes

ABSTRACT To investigate the deeper coloring mechanism of berry, the ‘Benitaka’ (Be) grape, ABA treatment on ‘Benitaka’ (Be (ABA)), and its deeper coloring bud mutation ‘Brasil’ (Br) grape were compared three weeks post-ABA treatment (11 weeks post-flowering, 200？mg/g ABA). Firstly, the ABA-treated group exhibited a deeper coloring at three weeks post-ABA treatment than the ‘Brasil’. Deeper color in ‘Brasil’ was caused by higher content of peonidin-3-O-monoglucoside, malvidin-3-O-monoglucoside, and malvidin-3-O-coumarylglucoside, while the deeper color in ABA-treated group was mainly caused by higher content of cyanidin-3-O-monoglucoside and peonidin-3-O-monoglucoside. In addition, the results revealed that ‘Brasil’ showed deeper coloring than ‘Benitaka’ was probably due to the higher expression of the VvmybA1 and VvmybA1-1 genes, similar with ABA-treated group. Compared with ‘Benitaka’, the distinction between the ABA-treated group and ‘Brasil’ was the expression of VvmybA1 gene. The gene expression was delayed in the ABA-treated group until three weeks post treatment. The VvmybA1 gene and transcription factor play an important role in the anthocyanin biosynthesis, and showed the difference in expressions of the VvmybA1 and VvmybA1-1 gene during different period of time probably due to different kind of anthocyanins. Based on these results, a possible mechanism of anthocyanins biosynthesis was established to elaborate the reason for the deeper coloring in ABA-treated ‘Benitaka’ and ‘Brasil’ grapes