Biopolymers and cell. 1998; 14 (4): 298 - 319

Genome variability in plan! somatic cells;. 4. Variability in the process of dedifferentiation and callus formation in vitro

V. A. Kunakh

Peculiarities of the genome, variations upon induction of the dedifferentiation and callus formation events have been reviewed. Role of the genotype and the. genome state in cells of the original explant, nutrient medium stimuli, determinants, mechanisms and possible ways to control these variations have been discussed. Initiation of the dedifferentiation processes and further cell pro¬liferation was shown to suggest the reprogra.mming of the genome, «iuvenilization» of its state. Genome regressive evolution in the course of the development of the dedifferentiation program was hypothesized. Capacity for such evolution seems to underly the differentiation—dedifferentiation—^differentiation developmental cycle peculiar to many plants. Existence of such a cycle, its potential to be control-liable both in nature and experiment appear to question the concept about the programmed number of the cell cycles, the irreversibility of ageing, tile fatality of the programmed cell death and. apoptosis. Utmost importance and actuality of the studies on molecular mechanisms of the dedifferentiation and juvenilization processes in plants has been emphasized. Author believes that this would allow better understanding of the fundamental biological mechanisms involving ageing and death.