For several years, at the Department of Plant Physiology, Institute of Biology, SGGW some intensive research on the influence of non-protein amino acids on the metabolism of plant cells have been carried out. As part of the Preludium project "Mechanism of the toxic effect of canavanine on root growth: disruption of the organization of the root apex, ultrastructure of cells, the cell cycle and auxin transport”, the scientists are trying to answer the question, to what extent the tomato root growth disturbance observed in the presence of canavanin are caused by a disturbance in the course of the cell cycle. The data obtained may be some day the basis for explaining the validity of canavanine-assisted anti-cancer therapy.