[Unintended effects of genetic modifications in plants and methods of their analysis].

The problem of unintended effects caused by genetic modification of plants is analysed. Factors that can provoke the unintended effects in genetically engineered plants, their consequences and possibility of the avoiding of unintended effects with use of current methods of genetic modification are discussed. Modern methodological approaches applied to analyse the unintended effects during the safety assessment of transgenic plants, in particular methods of molecular profiling with different "-omic"-technologies are described.

Adaptation and impairment of DNA repair function in pollen of Betula verrucosa and seeds of Oenothera biennis from differently radionuclide-contaminated sites of Chernobyl.

BACKGROUND AND AIMS: The plants that have remained in the contaminated areas around Chernobyl since 1986 encapsulate the effects of radiation. Such plants are chronically exposed to radionuclides that they have accumulated internally as well as to alpha-, beta- and gamma-emitting radionuclides from external sources and from the soil. This radiation leads to genetic damage that can be countered by DNA repair systems. The objective of this study is to follow DNA repair and adaptation in haploid cells (birch pollen) and diploid cells (seed embryos of the evening primrose) from plants that have been growing in situ in different radionuclide fall-out sites in monitored regions surrounding the Chernobyl explosion of 1986. METHODS: Radionuclide levels in soil were detected using gamma-spectroscopy and radiochemistry. DNA repair assays included measurement of unscheduled DNA synthesis, electrophoretic determination of single-strand DNA breaks and image analysis of rDNA repeats after repair intervals. Nucleosome levels were established using an ELISA kit. KEY RESULTS: Birch pollen collected in 1987 failed to perform unscheduled DNA synthesis, but pollen at gamma/beta-emitter sites has now recovered this ability. At a site with high levels of combined alpha- and gamma/beta-emitters, pollen still exhibits hidden damage, as shown by reduced unscheduled DNA synthesis and failure to repair lesions in rDNA repeats properly. Evening primrose seed embryos generated on plants at the same gamma/beta-emitter sites now show an improved DNA repair capacity and ability to germinate under abiotic stresses (salinity and accelerated ageing). Again those from combined alpha- and gamma/beta-contaminated site do not show this improvement. CONCLUSIONS: Chronic irradiation at gamma/beta-emitter sites has provided opportunities for plant cells (both pollen and embryo cells) to adapt to ionizing irradiation and other environmental stresses. This may be explained by facilitation of DNA repair function.

[Genetic disorders in the pollen cells of waxy barley in radioactive contamination after the Chernobyl accident]. / Geneticheskie narusheniia v pyl'tsevykh kletkah iachmenia waxy v usloviiakh radioaktivnykh zagriaznenii posle Chernobyl'skoi avarii.

Genotoxic effects during microsporogenesis and gametogenesis were studied in barley of the waxy strain grown on 3 experimental plots situated in the region of the Chernobyl disaster (plot 1 in the town of Chernobyl, plots 2 and 3 in the town of Yanov, 3 km away from the damaged power plant). It was determined that an increased level of radionuclide pollution and chronic irradiation during ontogenesis results in higher incidence of meiotic disturbances and abnormalities during formation of the male gametophyte. Incidence of waxy reversions in pollen grains depends on the activity of radionuclide pollutants as well. We suggest that selection affecting both diplont and haplont forms will provide for the absence of significant aberrations in subsequent plant generations.