Physiological Responses of Banana Fruit to Two Structural Analogues of 1-MCP as Ethylene Action Inhibitors

Ethylene induced actions during fruit ripening have been found to be inhibited by 1-methylcyclopropene (1-MCP) and possibly its analogues by competing for the sites of binding on the ethylene receptor. The purpose of this study was to evaluate the effect of treatment with 1-PentCP or 1-OCP, two structural analogues of 1-MCP, on inhibiting ethylene action in banana (Musa sapientum L.) fruit. The banana fruit after being fumigated for 20 h at 20±2°C with 0 (control), 0.4, 0.8 or 1.2 μl l-1 of 1-MCP, 1-PentCP or 1-OCP were stored in air environment at 20±2°C for ripening assessment. Ethylene production, color change, firmness, ACS activity, ACO activity and ACC content of the fruits were measured every 5 days during storage. The results of our study showed that these two structural analogues, just as 1-MCP, exerted their effect in a concentration-depended manner. 1-OCP was found to inhibit ethylene-induced ripening of banana fruit at a low concentration relatively. Treatment for 20 h with 0.8 μl l-1 1-OCP or 1.2 μl l-1 1-PentCP all delayed ethylene climacteric peak of banana fruit by 10 days as compared with the untreated group, after which the banana fruit resumed normal ripening. Softening and color change of banana fruit was restrained by the two structural analogues. Increasing the concentration of 1-PentCP to 1.2 μl l-1 caused a marked delay in softening and color change, but increasing the concentration of 1-OCP to 1.2 μl l-1 or higher did not result in a further delay in softening and color change. The results indicated that treatment with 0.8 μl l-1 1-OCP is sufficient to exert maximal delay of banana fruit ripening. Treatment with the most effective concentration of 1-OCP or 1-PentCP delayed ACC content, ACS activity and ACO activity of banana fruit as compared with the untreated group, but less effective than 1.2 μl l-1 1-MCP. It is suggested that 1-OCP was found to be a more potent inhibitor of banana fruit ripening than 1-PentCP, but less potent than the mother compound 1-MCP. The two structural analogues are beneficial to fruit storage and enhance the fruit resistance to decay that can be promised to be applied in agricultural practice.