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

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.

为探究浆果更深色的着色机制，本研究以‘本富’（Benitaka，简称Be）葡萄、经脱落酸(Abscisic Acid, ABA)处理的‘本富’葡萄（Be (ABA)）以及其更深色着色芽变品种‘布拉西尔’（Brasil，简称Br）葡萄为材料，在ABA处理后3周（即开花后11周，ABA施用浓度为200 mg/g）开展比较分析。首先，ABA处理组在ABA处理后3周的着色程度较‘布拉西尔’更为显著。‘布拉西尔’的更深色着色源于其芍药素-3-O-单葡萄糖苷(peonidin-3-O-monoglucoside)、锦葵素-3-O-单葡萄糖苷(malvidin-3-O-monoglucoside)以及锦葵素-3-O-香豆酰葡萄糖苷(malvidin-3-O-coumarylglucoside)含量更高；而ABA处理组的更深色着色则主要由矢车菊素-3-O-单葡萄糖苷(cyanidin-3-O-monoglucoside)与芍药素-3-O-单葡萄糖苷含量提升所介导。此外，研究结果表明，‘布拉西尔’较‘本富’着色更深，可能与其VvmybA1与VvmybA1-1基因的高表达有关，这与ABA处理组的情况一致。相较于‘本富’，ABA处理组与‘布拉西尔’的差异体现在VvmybA1基因的表达模式上：ABA处理组的VvmybA1基因表达延迟至处理后3周才被激活。VvmybA1基因及其编码的转录因子在花青素生物合成过程中发挥关键作用，二者在不同时段的VvmybA1与VvmybA1-1基因表达量存在差异，这可能与葡萄中所含花青素的种类不同有关。基于上述研究结果，本研究构建了一种潜在的花青素生物合成机制模型，以阐明经ABA处理的‘本富’葡萄与‘布拉西尔’葡萄着色更深的分子机理。