CYTOGENETIC EFFECTS IN BARLEY ROOT APICAL MERISTEM AFTER EXPOSURE OF DRY SEEDS TO LITHIUM ION BEAMS

In order to analyze the cytogenetic effects of high linear energy transfer radiation, dry barley seeds were irradiated with 7Li-ions. Three reconstructed barley (Hordeum vulgare L.) karyotypes D-2946, T-46, T-29 and their parental genotype Freya were used in the study. Various types of chromosome aberrations were observed in metaphase preparations stained with Feulgen. Chromosomal aberrations of both chromatid and chromosome type were found which indicates that 7Li-ions display S-independent mode of action. The frequency of chromosomal abnormalities was relatively low due either to the reduced clastogenic potential of the radiation doses applied or to the influence of cell cycle progression and elimination of the damaged cells. Fluorescence in situ hybridization with pTa71 and GAA repetitive DNA probes was performed. Hybridization with probe pTa71 revealed chromosome translocation between the two satellite chromosomes 5H and 6H resulting in a combination of both NORs containing ribosomal repeats in one and the same chromosome in line T-46 exposed to 45 Gy 7Li-ions. As the observed abnormality equally affects the entire cell population of a single primary root this might be a plausible evidence of its spontaneous nature.