Table_4_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（*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青素（anthocyanins），该类物质具备极强的抗氧化能力（antioxidant capacity）。然而，由于蓝莓属于非模式植物，学界对其花青素合成相关的结构基因与调控基因的认知仍较为匮乏。既往研究发现，在"Jersey"高丛蓝莓果实的绿熟后期喷施1000 mg/L脱落酸（abscisic acid，ABA），可提升其花青素含量。本实验以"Brightwell"兔眼蓝莓果实为材料，对前述研究结果进行验证。基于既往研究成果，本研究将蓝莓从绿熟后期至完全成熟的花青素积累过程划分为六个阶段，并借助转录组（transcriptome）技术系统解析蓝莓的花青素合成通路。结合已发表的植物花青素合成调控关键转录因子相关研究数据，构建系统发育树（phylogenetic trees），以探究蓝莓果实成熟过程中的关键转录因子。研究结果表明，脱落酸在果实转色期（veraison）可提升蓝莓果实的花青素含量。本研究鉴定得到花青素通路中的全部结构基因与转录因子（MYB、bHLH及WD40家族），并分析了它们的时空表达模式。经脱落酸处理的果实中，CHS、CHI、DFR及LDOX/ANS的表达量在成熟最后两个阶段显著上调，这与果实花青素含量的变化趋势一致。总体而言，本研究共筛选得到6个MYB转录因子、1个bHLH转录因子及4个WD40转录因子，它们在果实成熟过程中经脱落酸处理后表达量发生显著变化。其中，VcMYBA在脱落酸信号通路调控花青素合成过程中发挥核心作用。本研究结果初步阐释了脱落酸提升蓝莓花青素含量的作用机制，可为蓝莓花青素的工业化利用效率提升提供理论支撑。