Effect of exogenous polyamines on Scots pine callus in vitro

Callus cultures were started from buds of mature Scots pines (Pinus sylvestris L.) and exogenous putrescine, spermidine and spermine were added to the growth medium in order to test their capacity to reduce browning and poor callus growth. Spermine (1 mmol/L) inhibited callus growth as measured in terms of dry weight. The effect of 1 mmol/L putrescine was studied more closely using two types of growth medium (Krogstrup and modified Murashige and Skoog), and its influence on callus growth and development was determined by measurements of dry weight, enzyme activities (arginine decarboxylase 4.1.1.19, ornithine decarboxylase 4.1.1.17 and phenylalanine ammonia-lyase 4.3.1.5), ethylene production, synthesis of soluble proteins and levels of free polyamines in calli. It was found to increase ethylene production in the callus, while its effect on protein synthesis, ADC and PAL activities depended on the growth medium, and changes in these react ions were seen in poorly growing callus in the form of decreases in ADC activity while PAL activity and the concentrations of two small polypeptides increased. High values of free putrescine were measured in calli in the presence of putrescine, but the concentrations of free spermidine and spermine did not clearly change. The results suggest that exogenous polyamines affect metabolism in pine callus but cannot prevent browning and deterioration.