Quantitative description of early transcriptional response of plant cells to radiation-induced DNA damage using a Poisson initiation event model

Aim. One of the problems that have not lost their relevance is the study of the mechanisms of adaptation of higher plants to the effects of radiation associated with the modification of the DNA repair system in response to radiation. This paper presents a Poisson mathematical model of the radiation-induced early transcriptional response of genes of key enzymes, which catalyze recovery of double-stranded DNA breaks in active plant cells. Methods. We used total X-ray irradiation of a model object – 35-day-old Arabidopsis thaliana (L.) Heynh plants at sublethal doses of 3-21 Gy, total RNA extraction, reverse transcription with random hexanucleotide primers, PCR amplification of the obtained cDNA with primers to target genes, fluorescence gel densitometry of amplified products. Results. A mathematical model of transcriptional response to the genotoxic action of ionizing radiation in a subpopulation of active plant cells based on Poisson distribution, which satisfactorily describes the experimental data obtained, is proposed. Conclusions. To initiate a maximal transcriptional response to DNA damage, one two-strand lesion per chromosome, detected by DNA repair systems, is sufficient, while the absence of double-stranded lesions, or the appearance of more than one double-stranded lesion per chromosome inhibits early transcriptional response of the cell on the action of ionizing radiation. The Poisson model of the initiating event makes it possible to predict the response of subpopulations of active cells of angiosperms to the action of genotoxic factors. Keywords: ionizing radiation, DNA damage response (DDR), Arabidopsis thaliana, DNA repair, gene transcriptional activity.