Ethylene Production in Kiwifruit

Kiwifruits (Actinidia chinensis Planch. cv. Hayward) produced ethylene at an increasing rate at 21°C after exceeding a threshold level of 0.1μlkg-1h-1. There was a wide variation in time before the burst of ethylene production by individual fruits was evident after transferred from 1°C to 21°C. This variation became less and the time necessary for individual fruits to reach the increased level of ethylene became shorter and uniform as the storage period at a low temperature (1°C) extended. The increased rate of ethylene production was paralleled by the increased internal ethylene concentration and accompanied by the rise in respiration and soluble solids content and flesh softening. 1-Aminocyclopropane-1-carboxylic acid (ACC) content in the fruit tissue increased in parallel with the rise in the rate of ethylene production. ACC synthase activity also increased in the ethylene forming tissue. Ethylene forming enzyme (EFE) activity increased with the increase in the rate of ethylene production by the fruit. Ethylene production by the fruit tissue was strongly inhibited by aminoethoxyvinylglycine (AVG). EFE activity in the tissue was strongly inhibited by Co2+, n-propyl gallate (PG) and sodium caprylate (CAP). These results may indicate that ethylene biosynthesis in the kiwifruit proceeds along the methionine and ACC pathway.