Ethylene biosynthesis and respiration during ripening in mango cultivars

ACC-oxidase and ACC-synthase enzyme activities were determined at different stages of ripening in two varieties of mango fruits (Mangifera indica L.), viz. Amrapali and Dashehari. An increase in ACC-synthase enzyme activity from mature green stage to over ripe stage was recorded in both the cultivars. ACC-oxidase activity however showed a gradual decline with the advancement in ripening resulting in accumulation of aminocyclopropane-1-carboxylic acid (ACC). In presence of amino-oxyacetic acid (AOA, 50 μM), a competitive inhibitor of ACC-synthase, several fold decline in the enzyme activity was noted. Among the two cultivars Dashehari showed higher level of ACC-synthase and ACC accumulation, and low level of ACC-oxidase, and ethylene production compared to Amrapali during the ripening process. Higher respiration rate accompanied by ethylene production were recorded in Amrapali.