PHENYLALANINE AMMONIA-LYASE (PAL) ACTIVITY AND ITS RELATIONSHIP TO ANTHOCYANIN AND FLAVONOID LEVELS IN NEW ZEALAND-GROWN APPLE CULTIVARS

Phenylalanine ammonia-lyase (PAL) activity was measured in a range of New Zealand-grown apple (Malus domestica Borkh.) cultivars at three st ages of fruit development. Anthocyanin and total flavonoid levels were also measured (by HPLC) in the same fruit, There was wide variation i n the level of PAL activity, anthocyanin and total flavonoid levels in different apple cultivars and at different stages of development. The re was no apparent correlation between average PAL activity over the t hree developmental stages and final anthocyanin concentration (r = 0.3 4, P > 0,1), but there was significant correlation between average PAL activity over the three developmental stages and the final concentrat ion of total flavonoids (r = 0.75, P < 0.02). An inhibitor, PAL-IS, wa s also assayed in the same fruit but no correlation was found between PAL-IS and final anthocyanin levels (r = -0.30, P > 0.1) or total flav onoid levels (r = 0.15, P > 0.1). These results suggest that PAL activ ity has an influence on total flavonoid levels in the fruit but that P AL-IS does not. Anthocyanin levels are likely controlled at a point in the flavonoid pathway other than PAL or PAL-IS.