Integrated transcriptomic and Metabolomic insights into the dynamic changes in gene expression and secondary metabolites in gibberellin-treated grape berries

The quality and color of grape berries are crucial during the post-flowering development process. Gibberellin is a vital in the various physiological stages of fruit plant development in horticulture. Due to the limited understanding of how gibberellin affects grape quality and color, we hypothesized that it regulates berry coloration and quality by modulating gene expression and metabolism. Therefore, transcriptomic and metabolomic analyses were conducted at multiple time points after gibberellin treatment to study the mechanisms governing quality and formation of color during grape development. A total of 188.38 Gb of clean data and 311 flavonoid metabolites were obtained by RNA-Seq and LC-MS/MS determination after treatment with different concentrations of gibberellin. The auxin response genes, ethylene response transcription factors, brassinosteroid (BR) regulation genes, gibberellin-related TFs (GRAS), and saccharide-regulated DEGs (beta-glucosidase and trehalose 6-phosphate synthase) were significantly induced by gibberellin to regulate the development of grapefruit. Key genes involved in flavonoid biosynthesis, including CHS, flavonoid' 3',5'-hydroxylase, and flavonoid O-methyltransferase, were also significantly induced by gibberellin. However, ferulate 5-hydroxylase in lignin biosynthesis was significantly down-regulated. Moreover, the detection results of the related enzyme activities (PAL, UFGT, DFR, and ANS) and metabolite content (phenol, flavonoid, and anthocyanin) were also consistent with the gene expression trend. The results of this experiment indicate that the key metabolic compounds and genes responsive to gibberellin treatment participate in fruit color metabolism and quality composition formation of grapes.