Comparison of anthocyanin synthesis of true-to-type `Tsugaru' apple and its red sport strains

Summary

The effects of light and temperature on anthocyanin accumulation in `Tsugaru' red sport strains, `Homei' and `Misuzu' were compared with true-to-type `Tsugaru' apple. The fruit of the red sport strains developed their red colour earlier than `Tsugaru', and `Homei' contained much more anthocyanin both on the blush side and the shaded side of the fruit on the tree. Both red strains accumulated much more anthocyanin than `Tsugaru' under white plus ultraviolet light of 280-320 nm (+UV), and under white light (-UV). The responsiveness of `Homei' to -UV light was greater than that of `Tsugaru' and `Misuzu'. The optimum temperature for highest anthocyanin production changed from 158C to 208C with advance of fruit ripening in all strains. There were no clear differences between `Tsugaru' and red strains for anthocyanin accumulation in response to temperature. Phenylalanine-ammonia lyase (PAL) activity has been investigated in relation with anthocyanin accumulation.