EFFECT OF EXOGENOUS POLYAMINES AND INHIBITORS OF POLYAMINE BIOSYNTHESIS ON GROWTH AND FREE POLYAMINE CONTENTS OF EMBRYOGENIC SCOTS PINE CALLUS

Effects of the exogenously added polyamines putrescine, spermidine and spermine and the inhibitors of polyamine biosynthesis, methylglyoxal bis(guanylhydrazone) (MGBG) and dicyclohexylamine (DCHA), in the DCR m edium on the endogenous polyamine levels and growth of embryogenic cal lus of Scots pine (Pinus sylvestris L.) were studied. With polyamine t reatments the endogenous putrescine level was significantly affected o nly by 10 mu mol/L spermidine, which decreased the putrescine. Other p olyamine treatments did not have an effect on the putrescine level. En dogenous spermidine or spermine levels were not significantly affected by exogenous polyamines, although lower spermine concentrations were found in callus tissues with all polyamine supplements. DCHA significa ntly reduced the endogenous putrescine level but nor the spermidine or spermine levels. The highest concentration of MGBG (5 mmol/L), but no t the lower ones (0.1 and 1 mmol/L), reduced putrescine, spermidine an d spermine levels. The callus tissues cultured with exogenous polyamin es or inhibitors showed a positive correlation between endogenous putr escine and the relative growth rate (R-G) The correlation was also pos itive between the endogenous spermidine and R-G, but no correlation wa s found between the endogenous spermine and R-G. Exogenous polyamines did not affect: the growth of the callus tissues. All DCHA treatments (0.1, 1.0 and 5 mmol/L) inhibited the growth of the calli, whereas MGB G inhibited the growth only with the highest concentration (5 mmol/L).