Polyamines, abscisic acid and ethylene production in tomato fruit

Tomato fruit of the fast-ripening cultivar Breton had higher rates of ethylene production than the slow-ripening cultivar Daniela. The initial abscisic acid values were high in both cultivars, but fell during the first six weeks of development. After this time the levels increased, reaching a maximum before ethylene production began to increase. This maximum was much more pronounced in the fast-ripening cultivar. The polyamine/ethylene ratio also differed, with the slow-ripening cultivar having higher levels of putrescine and lower levels of ethylene. In this cultivar, putrescine was the major polyamine throughout, and it increased sharply during the ripening stage. Spermidine levels, on the other hand, decreased gradually, especially during the first two weeks of development.