Comparison of anthocyanin components, expression of anthocyanin biosynthetic structural genes, and TfF3′H1 sequences between Tulipa fosteriana ‘Albert heijn’ and its reddish sport

• A pink flower tulip cultivar AH and its reddish flower bud sport SN09 were compared.
• Anthocyanin components in petals of AH and SN09 were identified by UPLC–Q-TOF–MS.
• Cyanidin derivatives content and TfF3′H1 transcription were significantly lower in SN09.
• Insertion mutation in TfF3′H1 promoter in SN09 greatly reduced TfF3′H1 transcription.

A reddish flower tulip sport Tulipa fosteriana ‘SN09’ was bred from a pink flower cultivar T. fosteriana ‘Albert heijn’ (AH). To investigate the molecular basis underlying this color difference, SN09 and AH were compared using biochemical and molecular approaches. Ultra performance liquid chromatography (UPLC) profiles revealed that major cyanidin 3-rutinoside and minor pelargonidin 3-rutinoside were accumulated in the petals of AH, whereas major pelargonidin anthocyanins (pelargonidin 3-acetylrutinoside and pelargonidin 3-rutinoside) and minor cyanidin 3-glucoside were detected in SN09. The total anthocyanin content in petals of AH and SN09 were not significantly different at Stage 4, and correlated with the expression patterns of dihydroflavonol 4-reductase (TfDFR1) and anthocyanidin synthase (TfANS1). In addition, more transcripts of chalcone synthase (TfCHS1), chalcone isomerase (TfCHI2), and flavanone 3-hydroxylase (TfF3H1) contributed to higher accumulation of flavone and flavonol in SN09 than in AH. The transcription of flavonoid 3′-hydroxylase (TfF3′H1) was significantly lower in SN09 than in AH throughout flower development. Accordingly, the nucleotide sequences of TfF3′H1 in AH and SN09 were compared. Results showed that the deduced amino acids of TfF3′H1 in AH and SN09 were not different, but an extra fragment (255 bp) was found in the promoter of TfF3′H1 in SN09. Consequently, the promoters of TfF3′H1 in AH and SN09 were isolated, fused with the β-glucuronidase (GUS), and then transformed to tobacco and Arabidopsis thaliana. Results demonstrated that the GUS activity in Arabidopsis with TfF3′H1 promoter from SN09 was only 5.4% of that from AH, suggesting that the insert mutation in the TfF3′H1 promoter hampered the accumulation of cyanidin anthocyanins in SN09 through the reduction of TfF3′H1 transcription.