Disintegration of nuclear DNA into HMW-DNA fragments in plant nuclear and protoplast preparations

I.O. Andreev, K.V. Spiridonova, A.N. Zelensky, V.T. Solovyan, V.A. Kunakh

Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, UA252143, Ukraine. E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it.

Using preparations of plant nuclei and protoplasts embedded in agarose the process of nuclear DNA disintegration into high molecular weight fragments has been studied.

Our results show that in the presence of Mg2+ ions there occurred the autodigestion of nuclear DNA into high molecular weight fragments. Incubation of the preparations in the presence of EDTA or with increased NaCl concentrations (from 0 to 150 mM) prevented the fragmentation process.

Extraction of preparations with 2M NaCl which allow to remove the bulk of the nuclear proteins practically failed to change the efficiency of Mg2+- dependent nuclear DNA cleavage into HMW fragments. Nuclear DNA HMW fragmentation pattern was found to vary with the particular plant tissue. In the presence of Mg2+ ions differentiated tissues showed more pronounced DNA disintegration than the proliferating ones.

Our results allow to suppose the involvement of the specific nuclease activity in the process of nuclear DNA disintegration into HMW fragments. This activity appears to be associated with the residual nuclear structures resistant to extraction with 2M NaCl (nuclear matrix and dependent on functional (proliferative) status of the tissue.