Effects of inhibitors on the carbon dioxide-stimulation of ethylene-forming enzyme activity in fruit of Japanese pear and apple

Abstract

Abstract Cobalt ions (Co 2+ ) at 1 mM inhibited ethylene-forming enzyme (EFE) activity and ethylene production in apple (Granny Smith) discs. Low concentrations (0.01 mM) of Co 2+ ions stimulated, but higher concentrations (>0.02 mM) inhibited EFE activity in discs of both Japanese pear (Hosui) and apple. CO 2 stimulated EFE activity but did not reverse the inhibition caused by Co 2+ ions. AgNO 3 inhibited ethylene production of fruit discs in Granny Smith apple. Low concentrations ( + stimulated, but higher levels (0.5 and 1 mM) inhibited EFE activity in discs of both fruits. CO 2 did not reverse the inhibitory effect of Ag + (1 mM). 2,5-Norbornadiene (NDE) at 0.5% (v/v) inhibited EFE activity in discs from both fruits. CO 2 partially reversed the NDE inhibition in discs of Hosui and Granny Smith fruit stored at 1 ± 1°C for a short period. The possible mechanisms of the interactions between CO 2 and the inhibitors on EFE activity and ethylene receptors are discussed.