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 mu M ABA blocked the growth and altered the level of K+ in both the shoot and root. The presence of ABA increased the putrescine titer during a 24-h treatment. Increasing the endogenous level of K+ by the addition of 10 mM KCl to the ABA-treated seedlings, inhibited the effect of ABA on growth and putrescine level. In both tissues, ABA increased putrescine content at low concentrations (1 mu M), reaching the maximal effect 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 ways, ornithine and arginine decarboxylase activities. These results are discussed in relation to ion balance under stress.