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.