MANIPULATION OF FLESH COLOUR IN FRUIT OF ACTINIDIA MACROSPERMA WITH METHYL JASMONATE

Fruit of A. macrosperma (C.F. Liang) are characterized by the change in flesh colour from green to vibrant orange during ripening. Colour changes are clearly visible through the transparent skin of the fruit and can be readily monitored non-destructively using a chroma meter. Colour changes occur over a relatively short period of about 2 weeks once mature but still green fruit are harvested. A. macrosperma fruit were used as a model system to study changes in flesh colour induced by methyl jasmonate. Methyl jasmonate is an oxylipin that has been shown to induce a wide variety of responses in plant tissues, including promoting fruit ripening, increasing ethylene production in climacteric fruit, and accelerating chlorophyll degradation and carotenoid synthesis. Fruit of A. macrosperma were harvested when still green (average hue 112.4°). Fruit were dipped in 0, 1 and 10 mM methyl jasmonate after harvest and were then held at 20°C for 2 weeks. Fruit flesh colour and ethylene biosynthesis were monitored during ripening. Methyl jasmonate at both concentrations (1 and 10 mM) accelerated the rate of colour change and promoted ethylene biosynthesis relative to the control. The results indicate that flesh colour change in A. macrosperma can be promoted by methyl jasmonate application, possibly mediated by ethylene production.