Functional and transcriptional regulation of the anthocyanidin acyl modifier gene Gs5AT of Gentiana sino-ornata

The Chinese gentian, Gentiana sino-ornata produces brilliant blue flowers. To investigate the biological function and transcriptional regulation mechanism of the anthocyanin 5-O-acyltransferase gene (Gs5AT) in the corolla, it is beneficial to analyse the mechanism of blue flower colour presentation. In this investigation, we obtained the CDS and promoter sequences of the gene Gs5AT. Yeast one-hybrid experiments were used to identify the transcription factor GsbHLH7 that activates the gene Gs5AT. According to quantitive reverse transcription polymerase chain reaction analysis, the expression of the gene Gs5AT was significantly and positively correlated with the gene GsbHLH7. The colour phenotype of the flowers was significantly altered by the virus-induced gene silencing transduction of Gs5AT and GsbHLH7, with GsbHLH7 silencing producing more pronounced changes in the corolla colour than Gs5AT. The expression of GsF3′5′H, GsDFR, GsANS, Gs3GT, and Gs5GT all fell to varying degrees after GsbHLH7 silencing, indicating that GsbHLH7 may regulate transcription of these genes as well as Gs5AT. The results of this study indicate that Gs5AT was positively regulated by the GsbHLH7, and thus affects the colour presentation of the blue corolla.