Transcriptome Analysis Revealed The Mechanism of Exogenous ABA Increasing Anthocyanins in Blueberry Fruit During Veraison

Background: Blueberry（ Vaccinium Spp）is a popular healthy fruit all over the world. The health value of blueberry is mainly due to the fact that blueberry is rich in anthocyanins, which have a strong antioxidant capacity. However, due to the fact that blueberry is a non model plant, little is known about the structural genes and regulatory genes involved in the anthocyanin synthesis of blueberries. Previous studies have found that spraying abscisic acid at the late green stage of blueberry fruit can increase the content of anthocyanins. Based on the former results, the anthocyanin accumulation process of blueberry can be divided into six stages from late green stage to mature stage to analyze the anthocyanin synthesis mechanism. In order to identify the important genes in the anthocyanin synthesis process of blueberry, the transcriptome analysis was conducted to explore the key genes in blueberry anthocyanin synthesis process. Results: The results showed that ABA could increase the anthocyanin content of blueberry fruits during the veraison. The effect of ABA on blueberry fruit development was systematically analyzed by KEGG and GO. All structural genes and transcription factors (MYB, bHLH and WD40) involved in 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 S5-S6, which was consistent with the change of anthocyanins in fruits.In general, six MYB transcription factors, one bHLH transcription factor and four WD40 transcription factors under treatment were found to have significant changes in transcripts during fruit ripening. Conclusions: Our results suggest that VcMYBA should play a major role in the regulation of anthocyanin synthesis in ABA signaling. This result preliminarily explained the mechanism of ABA increasing anthocyanin content and improves the efficiency of industrial use of blueberry anthocyanins.