Effect of N-hydroxyurea, mitomycin C and actinomycin D on tumour formation on the leaves of Kalanchoe daigremontiana

Abstract

The leaves of <em>Kalanchoe daigremontiana</em> wounded and infected with <em>Agrobacterium tumefaciens</em> were treated with single doses of inhibitors (hydroxyurea - 190, mitomycin - 0.5, actinomycin - 2 µ,g per leaf). After delaying the time' of dosage of inhibitors during five days after inoculation, changes in susceptibility of the system to antitumorous activity of analysed compounds were observed. In several hours after inoculation (period of the bacteria metabolic activity in wounds) all the inhibitors prevent strongly the tumour formation. At the time between 14 and 72 hours after inoculation, including the phase of tumour induction, the system becomes sensitive to the DNA synthesis inhibitors, particularly hydroxyurea. The intensified action of actinomycin appears again only about 60 hours after inoculation and lasts till the end of experiment (the initiation of the transformed plant cell proliferation). According to the literature the antitumorous effect of inhibitors could be connected with their action on the bacteria metabolism inside the host tissue. The activities of hydroxyurea and mitomycin in the second period correspond with the intensive DNA synthesis in plant cells, which is induced by wounding. The effect of actinomycin D in 60 hours after inoculation could depend upon the inhibition of the proliferation of the transformed host cells.