ALTERED FRUIT RIPENING AND LEAF SENESCENCE IN TOMATOES EXPRESSING AN ANTISENSE ETHYLENE-FORMING ENZYME TRANSGENE

Tomato plants in which the synthesis of ethylene-forming enzyme (EFE) had been inhibited by an anti-sense gene were used to study the role of ethylene in fruit ripening at the biochemical and molecular level. A reduction in total lycopene accumulation was observed in EFE-antisense fruit ripened both on and off the plant. The rate of over-ripening and fruit spoilage was also reduced in the EFE-antisense fruit. The degree of inhibition of ripening was shown to be dependent upon the stage of development at which the fruit were detached from the plant. The effects on ripening in EFE-antisense fruit were much more pronounced when fruit were detached from the vine before the onset of colour change, and were associated with changes in the level of accumulation of mRNAs homologous to a number of previously characterized ripening-related cDNAs. The retarded ripening of detached EFE-antisense fruit could be partially restored by ethylene treatment. In addition to changes observed in ripening fruit, a temporal delay in the onset of foliar senescence was observed in EFE-antisense plants, indicating that the physiological effects of the EFE-antisense gene, and the associated reduction in ethylene evolution, are not confined specifically to fruit ripening.