[Radiobiological studies on the behavior of normal and tumorous plant tissues cultivated in vitro].

Vegetable tumoral tissue are more radiosensitive than the homologous normal tissue. Tumoral tissue are more stimulated by yeast extract and yeast s-ARN than normal tissue. Yeast extracts and s-RNA extracts from yeast also restore more the growth of tumorous tissue than normal tissue, which were subjected to gamma radiation from 60Co. A mixture of mononucleotides obtained from fractionated s-RNA has the same stimulatory effect. It is suggested that the active principle from yeast and s-RNA is a cytokinin like substance, which have been detected in yeast extract and in soluble ribonucleic acid from yeast.