Histochemical Investigation of Alcohol Dehydrogehase, Glutamate Dehydrogenase and Α-esterase Activity in Low Temperature Stressed Tobacco Callus and the Effect of Cytokinins

The influence of the synthetic phenylurea cytokinin 4-PU-30 and of the adenin cytokinin kinetin on the chilling and freezing stress of tobacco callus was studied histochemically. The investigations were carried out immediately after the low-temperature stress and after 20 days cultivation. It was established that alcohol dehydrogenase and glutamate dehydrogenase activities decreased but esterase activity rose drastically after chilling and freezing in the presence of both cytokinins in the nutrient medium. After 20 days the alcohol dehydrogenase activity was restored more rapidly in the presence of 4-PU-30 than in the presence of kinetin in the nutrient medium. A tendency of restoring normal glutamate dehydrogenase, and α-esterase activities after freezing was observed only in the presence of 4-PU-30. It was concluded that 4-PU-30 added to the nutrient medium manifests higher chilling and freezing antistress activity as compared to kinetin.