Fig. 6
The changes of flavonoids content and the related genes expression during the chilling duration. a The flavonoids and anthocyanin pathway. CHS, chalcone synthase; CHI, chalcone isomerase; F3H, flavanone 3-hydroxylase; DFR, dihydroflavonol 4-reductase; ANS, anthocyanin synthase; 3GT, anthocyanidin 3-O-glycosyltransferase; 5GT, anthocyanidin 5-O-glycosyltransferase; MT, anthocyanidin methyltransferase; 7GT, anthocyanidin 7-O-glycosyltransferase; FLS, flavonol synthase; FNS, flavone synthase; Lu, luteolin; Ap, apigenin; Is, isorhamnetin; Qu, quercetin; Km, kaempferol; Cy, cyanidin; Pg, pelargonidin; Glu, glucoside; Hex, hexoside; Neo, neohesperidoside; Rut, rutinoside; Rob, robinobioside; Syr, syringic acid. b The relative content of anthocyanins in tree peony flower buds after 28 d chilling duration based on the results of LC-ESI-MS/MS. c The relative expression levels of key genes involving in anthocyanin biosynthesis. Data were represented as mean of three different determinations ± SD. Asterisks indicate statistically significant differences (one-way ANOVA, *P < 0.05, **P < 0.01, ***P < 0.001 and ****P < 0.0001)