Measurement of anthocyanin conentration
Anthocyanins were extracted using the method of Lotkowska et al. (2015). About 0.1g fresh sample of rapeseed leaves was homogenated in 1mL of anthocyanin extract buffer (1% v/HCl, 99% v/n-propanol), followed by incubation at 98°C for 3 min. After 10~12 hrs further incubation in the dark at room temperature, the mixture was centrifuged at 12,000 rpm for 10 min. 200 µL aliquots of the supernatant were measured absorbance at 535 nm and 650 nm by ELIASA (Spark, TECAN). Extraction buffer served as blank control.