| Abstract: | The biochemical basis of the different sensitivity to methotrexateof Daucus carota and Oryza sativa cell cultures has been investigated.Carrot cells have a dihydrofolate reductase activity about tentimes higher than rice cells. In addition, they show a loweruptake rate of the inhibitor. No relevant differences have beenfound in the Km value for the dihydrofolate of the two enzymesand in the degree of inhibition of their activity by methotrexate. Key words: Dihydrofolate reductase, Methotrexate resistance, Plant cell suspension cultures, Oryza sativa, Daucus carota |
