Table_5_Transcriptome Analysis Revealed the Mechanism by Which Exogenous ABA Increases Anthocyanins in Blueberry Fruit During Veraison.XLSX

Blueberry (Vaccinium spp.) is a popular healthy fruit worldwide. The health value of blueberry is mainly because the fruit is rich in anthocyanins, which have a strong antioxidant capacity. However, because blueberry is a non-model plant, little is known about the structural and regulatory genes involved in anthocyanin synthesis in blueberries. Previous studies have found that spraying 1,000 mg/L abscisic acid at the late green stage of “Jersey” highbush blueberry fruits can increase the content of anthocyanins. In this experiment, the previous results were verified in “Brightwell” rabbiteye blueberry fruits. Based on the previous results, the anthocyanin accumulation process in blueberry can be divided into six stages from the late green stage to the mature stage, and the transcriptome was used to systematically analyze the blueberry anthocyanin synthesis process. Combined with data from previous studies on important transcription factors regulating anthocyanin synthesis in plants, phylogenetic trees were constructed to explore the key transcription factors during blueberry fruit ripening. The results showed that ABA increased the anthocyanin content of blueberry fruits during veraison. All structural genes and transcription factors (MYB, bHLH, and WD40) involved in the anthocyanin pathway were identified, and their spatiotemporal expression patterns were analyzed. The expression of CHS, CHI, DFR, and LDOX/ANS in ABA-treated fruits was higher in the last two stages of maturity, which was consistent with the change in the anthocyanin contents in fruits. In general, six MYB transcription factors, one bHLH transcription factor and four WD40 transcription factors were found to change significantly under treatment during fruit ripening. Among them, VcMYBA plays a major role in the regulation of anthocyanin synthesis in ABA signaling. This result preliminarily explained the mechanism by which ABA increases the anthocyanin content and improves the efficiency of the industrial use of blueberry anthocyanins.

蓝莓（Blueberry，Vaccinium spp.）是全球广受欢迎的健康果品。其健康价值主要源于果实富含花色苷（anthocyanin），且花色苷具备极强的抗氧化能力。然而，由于蓝莓属于非模式植物，目前对于其参与花色苷合成的结构基因与调控基因的认知仍较为匮乏。此前有研究发现，在“泽西”（Jersey）高丛蓝莓果实的绿熟后期喷施1000 mg/L的脱落酸（abscisic acid，ABA），可提升其果实内的花色苷含量。本实验以“粉蓝”（Brightwell）兔眼蓝莓果实为材料，对上述研究结果进行了验证。基于前期研究结论，本研究将蓝莓从绿熟后期至完全成熟的花色苷积累过程划分为六个阶段，并通过转录组（transcriptome）技术系统解析了蓝莓的花色苷合成通路。结合此前关于植物花色苷合成调控关键转录因子的研究数据，本研究构建了系统发育树（phylogenetic tree），以探究蓝莓果实成熟过程中的核心转录因子。研究结果显示，ABA可在蓝莓果实转色期提升其花色苷含量。本研究鉴定得到了花色苷合成通路中所有的结构基因与转录因子（MYB、bHLH及WD40家族），并对其时空表达模式进行了分析。经ABA处理的果实中，CHS、CHI、DFR及LDOX/ANS的表达量在成熟过程的最后两个阶段显著升高，这与果实花色苷含量的变化趋势一致。总体而言，在果实成熟过程中，经ABA处理后共有6个MYB转录因子、1个bHLH转录因子及4个WD40转录因子的表达量发生了显著变化。其中，VcMYBA在ABA信号通路调控花色苷合成的过程中发挥核心作用。本研究结果初步阐明了ABA提升蓝莓花色苷含量的分子机制，可为蓝莓花色苷的工业化利用效率提升提供理论支撑。