Free polyamine contents and decarboxylase activities during tomato development and ripening

The levels of free polyamines (PAs) and the activities of arginine decarboxylase (ADC), ornithine decarboxylase (ODC), and S-adenosylmethionine decarboxylase (SAMDC) were measured in pericarp tissues of tomato fruit (Lycopersicon esculentum cv. Indalo) during development and ripening, Putrescine (Put) was the predominant PA during the early stages of growth (less than 1 g weight), while contents of spermidine (Spd) and spermine (Spm) were lower. The PA concentration clearly increased at the early stage of development, reaching a peak in fruits weighing 10 mg. ADC, ODC, and SAMDC activities also all peaked in fruits with 10 mg of fresh weight. The initial increase in PA levels occurred concomitantly with a rise in these decarboxylases. During ripening, levels of Spd declined and no pronounced changes in Put occurred. Given that these variations did not reflect decarboxylase activities, which increased slightly at the pink stage, PA catabolism or conjugation might be involved in the ripening of this tomato variety.