Changes in activity of polyamine biosynthetic enzymes and in polyamine contents in developing fruit tissues of ‘Murcott’ mandarin

Arginine decarboxylase (ADC), ornithine decarboxylase (ODC), putrescine (Put) and spermidine (Spd) contents were analysed in growing ‘Murcott’ mandarin fruits from bloom to full development. Enzymes of polyamine synthesis and, to a lesser extent, polyamine contents roughly followed patterns of growth activity in fruit tissues, with a maximum at the early stages, a minimum at mid-summer and intermediate values at full fruit development. ADC/ODC and Put/Spd ratios were 2–8 and 2–30, respectively. Possible links between polyamine metabolism and citrus fruit set and development are suggested.