ABSCISIC-ACID INDUCED STRESS-LIKE POLYAMINE PATTERN IN WHEAT SEEDLINGS, AND ITS REVERSAL BY POTASSIUM-IONS

In 3-day-old wheat (Triticum aestivum L. cv. Marinat) seedlings, 100 m u M ABA blocked the growth and altered the level of K+ in both the sho ot and root. The presence of ABA increased the putrescine titer during a 24-h treatment. Increasing the endogenous level of K+ by the additi on of 10 mM KCl to the ABA-treated seedlings, inhibited the effect of ABA on growth and putrescine level. In both tissues, ABA increased put rescine content at low concentrations (1 mu M), reaching the maximal e ffect at 100 IJ M Putrescine increase induced by ABA was inhibited by both cu-difluoromethylarginine (DFMA) and Lu-difluoromethylornithine ( DFMO) in shoots while only the inhibitor of arginine decarboxylase was effective in the root. The presence of ABA modulated, in opposite way s, ornithine and arginine decarboxylase activities. These results are discussed in relation to ion balance under stress.