Effect of Bis(guanylhydrazones) on Growth and Polyamine Uptake in Plant Cells

In the present work the effect of several bis(guanylhydrazones) on the growth of Helianthus tuberosus tuber explants was studied. Different aliphatic congeners of glyoxal bis(guanylhydrazone) were tested. Most of the compounds displayed an inhibitory effect on growth, and a correlation between the structure of the molecule and the inhibitory activity was observed. Experiments carried out with glyoxal bis(guanylhydrazone) and its congeners methyl-, ethylmethyl-, and methylpropylglyoxal bis(guanylhydrazones) show that as the total number of side chain carbon atoms in the molecule increases, the inhibitory potency also increases. A depletion of spermidine levels was also found in the explants treated with ethylmethylglyoxal bis(guanylhydrazone), which turned out to be one of the most potent growth inhibitors. The addition of spermidine caused a significant reversion of the antiproliferative action of glyoxal bis(guanylhydrazone). The effect of these compounds on spermidine uptake in protoplasts isolated from carrot phloem parenchyma was also investigated. Only a slight competition was found when antagonists were present at concentrations 20 times higher than the polyamine, thus suggesting that bis(guanylhydrazones) do not share, at least at low concentrations, the polyamine transport system in plant cells. Received January 10, 1997; accepted January 22, 1999