The roles of methyl jasmonate (MJ) in lum fruit ripening, ethylene biosynthesis, and fruit quality were investigated using exogenous applications of MJ. Mature fruit of the early-, mid-, and late-maturing Japanese plum (Primus salicina Lindl.) cultivars 'Black Amber', 'Amber Jewel', and 'Angelino', respectively, were harvested at commercial maturity and exposed to 0,10 -5, or 10-3 M MJ vapour treatments at 20° ± 1°C for 12 h. Post-harvest MJ treatments accelerated fruit ripening processes in 'Black Amber', 'Amber Jewel' and 'Angelino' plum. Respiration rates, ethylene production, the activities of the ethylene biosynthetic enzymes 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and 1- aminocyclopropane-1- carboxylic acid oxidase (ACO), and the content of 1-aminocyclopropane-1- carboxylic acid (ACC) increased in MJ-treated fruit. Treatment with 10 3 M MJ advanced the ethylene climacteric in 'Black Amber' and 'Angelino' fruit by 2 d, compared to untreated fruit. Fruit exposed to MJ exhibited typical climacteric patterns of ACS and ACO activities, while control fruit did not show climacteric peaks in the activities of these enzymes. Application of MJ advanced the respiratory climacteric peak by 1 d in 'Amber Jewel' and 'Angelino' fruit, compared to control fruit. During fruit ripening, soluble solids contents (SSC) increased while titratable acidity (TA) decreased in MJ-treated fruit of all three cultivars. MJ application to 'Amber Jewel' and 'Angelino' fruit improved their colour in terms of L*, a*, b*, chroma and hue angle, while 'Black Amber' fruit did not exhibit any changes in colour parameters. MJ treatment also increased the synthesis of ascorbic acid, total carotenoids, and total anti-oxidants during fruit ripening in all cultivars.