This work was carried out to study the physiological behaviour of tomato fruits (Lycopersicon esculentum, Mill.), var. Kada, geneticaly transformed, via Agrobacterium tumefaciens, with the pMEL1 DNA clone, in antisense orientation, and nontransformed ones, from the same variety, growth in a greenhouse. The physiological study was conducted for evaluating the ripening cycle of fruits, ripened attached and detached from the plants in the mature-green stage , and their ethylene production. On average, tranformed tomatoes that ripened atached to the plants had a ripenig cycle of 27 days, whereas in detached fruits, this time was 50 days. Instead of it, nontransformed tomatoes showed a faster ripening process when ripened detached to the plants (20 days), whereas in attached fruits this period was 30 days, on average. These results were related to ethylene production. Tomato fruits from nontransformed plants produced 13,46 nL ethylene.g-1.h-1, and the transformed fruits showed an ethylene production almost 100 times smaller than nontransformed ones ( 0,13 nL ethylene.g-1.h-1). Thus, the conclusion reached is that the reduction of ethylene production observed in transgenic tomatoes is necessary but it is not enough to extend the ripening cycle and to increase the period of time that the fruits will last. To achieve this, it is necessary to harvest the fruits in the mature-green stage.
ACC oxydase; ethylene; tomato
