УРОВНИ ПЛОИДНОСТИ И ОТНОСИТЕЛЬНОГО СОДЕРЖАНИЯ ДНК В КУЛЬТУРЕ КЛЕТОК И ТКАНЕЙ РАСТЕНИЙ IN VITRO

Abstract

<p>We presented results of variations in the ploidy level and the genome size of the <em>R. acetosa</em> regenerants. These regenerants was obtained by indirect and direct morphogenesis in in vitro culture. Explants were prepared from seedlings on the three-leaf stage of plant development. More than 100 explants were used to stimulate the indirect and direct morphogenesis. Mesophilic explants were cultured on the MS nutrient medium containing auxin to callus proliferation (2 mg/L NAA, 1 mg/L BA). Cultivation of the callus was maintained for 4 weeks followed by an indirect morphogenes. Indirect morphogenesis stimulated on the MS medium with cytokinin and gibberellic acid predominance (0.5 mg/L BA, 0.2 mg/L GA3). Direct stimulate morphogenesis from the apical meristem of seedlings on nutrient media with a predominance of cytokinins (1 mg/L BA, 0.25 mg/L NAA). Rhizogenesis have stimulated by transferring of the regenerants to the ½MS medium supplemented with 0.2 mg/L of NAA. Research of a ploidy level and genome size was performed by flow cytometry used propidium iodide staining with <em>Vicia faba</em> cv “Innovec” (2C=26.90 pg) as internal DNA standard. We calculated the relative DNA content (2C) for <em>R. acetosa</em> equal to 6,98 pg. Cytogenetical analisis showed that the maximum genome size variation recorded for regenerants obtained through the indirect morphogenesis. Variations in the genome size of the regenerants obtained by direct morphogenesis deviates from the control group to 0.30 pg (2С=7.28 pg) and after indirect morphogenesis to 1.04 pg (2С=8.2 pg). Cytogenetical analysis of the regenerated plants showed the presence of different somatic chromosome numbers ranging from 2n = 14 to 2n = 28. The relative DNA content of tetraploid forms was 11.87 pg. In our study was shown, that the most effective method of plant conservation in the <em>in vitro</em> culture is a direct morphogenesis. Analysis of the relative nuclear DNA content and chromosome counts of regenerants obtained by indirect morphogenesis from the callus cultures showed significant variations in the DNA content, as well as the appearance of polyploid forms. Therefore, long-term cultivation of callus cultures increases the probability of genomic aberrations, which reduces the stability of the plant genome.</p>