Anthocyanin production in callus cultures of Cleome rosea: Modulation by culture conditions and characterization of pigments by means of HPLC-DAD/ESIMS

Leaf and stem explants of Cleome rosea formed calluses when cultured on MS medium supplemented with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) or 4-amino-3,5,6-trichloropicolinic acid (PIC). The highest biomass accumulation was obtained in the callus cultures initiated from stem explants on medium supplemented with 0.90 μM 2,4-D. Reddish-pink regions were observed on callus surface after 6–7 months in culture and these pigments were identified as anthocyanins. Anthocyanins production was enhanced by reducing temperature and increasing light irradiation. Pigmented calluses transferred to MS1/2 with a 1:4 ratio NH4+/NO3−, 70 g L−1 sucrose and supplementation with 0.90 μM 2,4-D maintained a high biomass accumulation and showed an increase of 150% on anthocyanin production as compared with the initial culture conditions. Qualitative analysis of calluses was performed by high performance liquid chromatography coupled to diode array detector and electrospray ionization mass spectrometry (HPLC-DAD/ESIMS). Eleven anthocyanins were characterized and the majority of them were identified as acylated cyanidins, although two peonidins were also detected. The major peak was composed by two anthocyanins, whose proposed identity were cyanidin 3-(p-coumaroyl) diglucoside-5-glucoside and cyanidin 3-(feruloyl) diglucoside-5-glucoside.