Anthocyanin accumulation and transcriptional regulation in purple flowering stalk (Brassicacampestris L. var. purpurea Bailey)

Key message 1. Purple flowering stalk (Brassica campestris L. ssp.chinensis L. var. purpurea Bailey) is a crop with the high-level anthocyanin. 2. Increased abundance of LBGs promoted the synthesis of anthocyanin. 3. TTG2 (WRKY) interacted with TTG1 (WD40), probably regulating anthocyanin accumulation by shaping a MBWW complex. Brassica crops are a class of nutrient-rich vegetables. Here, two Brassica Crops-Flowering Stalk cultivars, purple flowering stalk (Brassica campestris L. var. purpurea Bailey) and pakchoi (Brassica campestris ssp. chinensis var. communis) were investigated. HPLC-ESI-MS/MS analysis demonstrated that Cy 3-p-coumaroylsophoroside-5-malonylglucoside and Cy 3-diferuloylsophoroside-5-malonylglucoside were identified as the major anthocyanin in peel of purple flowering stalk. The transcript level of structural genes including C4H, CHS, F3H, DFR, ANS and UFGT, and regulatory genes such as TT8, TTG1, Bra004162, Bra001917 and TTG2 in peel of purple flowering stalk were significantly higher than that in peel of pakchoi. In addition, the TTG2(WRKY) interacted only with TTG1(WD40) and the interaction between TT8 (bHLH) and TTG1/Bra004162(MYB)/Bra001917(MYB) were identified. Else, the WD40-WRKY complex (TTG1-TTG2) could activate the transcript of TT12. Our study laid a foundation for the research on the anthocyanin accumulation in Brassica crops.

Automated summary

This study investigated two cultivars of Brassica crops, purple flowering stalk and pakchoi, and found that the purple flowering stalk has a higher level of anthocyanin compared to pakchoi. The study also identified several structural genes and regulatory genes that are involved in the accumulation of anthocyanin, as well as the interactions between these genes. The findings lay a foundation for further research on anthocyanin accumulation in Brassica crops.