Transcription Regulation of Anthocyanins and Proanthocyanidins Accumulation by Bagging in ‘Ruby’ Red Mango: An RNA-seq Study

The biosynthesis of anthocyanins and proanthocyanidins (PAs), components of two main flavonoids in plants, is regulated by environmental factors such as light. We previously found that bagging significantly repressed the biosynthesis of anthocyanins in red ‘Ruby’ mango fruit peel, but induced the accumulation of PAs. However, the molecular mechanism remains unclear. In the current study, transcriptome sequencing was used for screening the essential genes responsible for the opposite accumulation pattern of anthocyanins and PAs by bagging treatment. According to weighted gene co-expression network analysis (WGCNA), structural genes and transcription factors highly positively correlated to anthocyanins and PAs were identified. One flavanone 3-hydroxylase (<i>F3H</i>) and seven structural genes, including one chalcone synthase (<i>CHS</i>), one flavonoid 3’-hydroxylase (<i>F3’H</i>), one anthocyanidin synthesis (<i>ANS</i>), three leucoanthocyanidin reductase (<i>LARs</i>), and one UDP glucose: flavonoid 3-O-glucosyltransferase (<i>UFGT</i>), are crucial for anthocyanin and PA biosynthesis, respectively. In addition to MYB and bHLH, ERF, C2H2, HD-ZIP, and NAC are important transcription factors that participate in the regulation of anthocyanin and PA biosynthesis in ‘Ruby’ mango fruit peel by bagging treatment. Our results are helpful for revealing the transcription regulation mechanism of light-regulated mango anthocyanin and PA biosynthesis, developing new technologies for inducing flavonoid biosynthesis in mangos, and breeding mango cultivars containing high concentrations of flavonoids.