1-Methylcyclopropene (1-MCP) inhibits ethylene production of durian fruit which is correlated with a decrease in ACC oxidase activity in the peel

Fruit of cv. Monthong durian (Durio zibethinus Murr.) were treated for 12 h with 0 (control) and 500 nL L−1 1-methylcyclopropene (1-MCP) at 25 °C and were then stored at a temperature of 15°C. The fruit were transferred from a temperature of 15 °C to a temperature of 25 °C within a 3-day interval. 1-MCP treatment did not affect the relatively low rate of ethylene production in fruit stored at a temperature of 15 °C. In contrast, 1-MCP delayed the dramatic increase in ethylene production in fruit that were transferred from a temperature of 15 °C to a temperature of 25 °C. It is well known that the peel (husk) produces much more ethylene than the pulp, hence, the effects of 1-MCP on the peel will likely overshadow any effect on the pulp. In the peel, 1-MCP had no effect on 1-aminocyclopropene-1-carboxylic acid (ACC) synthase activity, but decreased ACO activity. ACC levels in the peel were not affected by the treatment at 25 °C. In the pulp, by contrast, ACO activity was not affected, but ACS activity was not inhibited at 25 °C and ACC levels were found to be lower, after the 1-MCP treatment. It was concluded that 1-MCP seems to inhibit ethylene production of durian mainly by preventing an increase in ACC oxidase activity in the peel.