Effects of 1-methylcyclopropene on activities of ethylene biosynthesis and cell wall degrading enzyme during ripening of papaya ‘Sekaki’

M. Razali, Z.M. Ali and R. Othman

Abstract

Ripening of papaya ‘Sekaki’ at ambient temperature was affected by application of 1-methylcyclopropene (1-MCP). The percentage weight loss of 1-MCP (270 ppb for 12 h) treated fruit was significantly (p <0.05) lower than control fruit. The loss of tissue firmness of 1-MCP treated fruit was significantly (p <0.05) inhibited, whilst the control fruit showed a dramatic loss in tissue firmness up to 50% yellowing-of-skin colour (YR) stage and then gradually until the end of ripening stage. The ethylene production increased significantly (p <0.05) to a maximum at 50% YR in 1-MCP treated and control fruits, and declining sharply thereafter. The 1-MCP treated fruits showed significant (p <0.05) reduction in ethylene production, 1-aminocyclopropane-1-carboxylic oxidase (ACO) and 1-aminocyclopropane-1-carboxylic synthase (ACS) activities but generally maintained the 1-aminocyclopropane-1-carboxylic acid (ACC) level. The activity of α- and β-galactosidase and pectin methylesterase (PME) was significantly (p <0.05) suppressed as compared to control fruit. The capability of 1-MCP to maintain the firmness of ‘Sekaki’ papaya during ripening might be associated with suppression of ethylene dependent cell wall degrading enzyme activities such as α- and β-galactosidases, PME, α-arabinosidase, α-mannosidase and β-glucosidase. This study showed the effectiveness of 1-MCP in delaying fruit ripening, significantly suppressing the cell wall degrading enzyme activity and maintaining the firmness of ‘Sekaki’ papaya fruit during ripening.

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