The effects of sodium azide and 2,4-dinitrophenol on caspase-like activation and peel spotting reduction of harvested 'Sucrier' banana fruit

Abstract

Prevention of cellular ATP production has been shown to inhibit caspase activation and apoptosis. Here, we investigated the effects of nonlethal doses of the ATP synthesis inhibitors, sodium azide (NaN3) and 2,4-dinitrophenol (DNP) on caspase-like activation related to cell death and the peel spotting disorder of harvested 'Sucrier' bananas. Treatments with NaN3 (50 and 100 μM) and DNP (50 and 100 μM) were shown to suppress cellular ATP levels and caspase-like protease (caspase 9 and caspase 3-like protease) activities, accompanied by a decrease in peel spotting in a dose dependent manner. Treatments with DNP (at the concentration of 100 μM) and NaN3 (at the concentration of 100 μM) were effective in reducing ATP levels, caspase-like activities and peel spotting. The decrease in ATP levels improved the cell viability by retarding program cell death activation, indicated by the lower caspase-9 and caspase-3-like activities. These results suggest that NaN3 and DNP could inhibit the caspase-like protease activation and delay the development of peel spotting. Therefore, caspase activation and cell death were dependent on ATP and associated with peel spotting development of 'Sucrier' banana.