Assessment of the Cytogenetic Damage Induced by Chromium Short-Term Exposure in Root Tip Meristems of Barley Seedlings

摘要

Heavy metals are determinant factors in increasing environmental pollution, and chromium is considered to be of highest concern because of its genotoxicity in microorganisms, animals, and humans. Relatively few studies are focused on the injury induced in plant genetic material. Therefore, the main objective of this work was to evaluate the extent of the cytogenetic damage induced in root meristems of barley (Hordeum vulgare L.) after short-term seed exposure to 10, 100, 250, and 500 μM K_2Cr_2O_7 (Gr(Ⅵ) concentration is 1.04, 10.39, 25.99, and 51.99 μg ml~(-1)) and 10, 100, 250, and 500 μM CrCl_3 (Cr(Ⅲ) concentration is 0.52, 5.19, 12.99, and 25.99 μg ml~(-1)). Chromium genotoxic potential was proved by significant increases in the rates of the ana-telophase chromosomal aberrations (1.3-2.3 times higher for K_2Cr_2O_7 and 1.7-2.2 times higher for CrCl_3, as compared to the control;p＜0.05, p＜0.01) and of metaphase disturbances (5.0-7.5 times more numerous in chromium-treated groups than in control; p＜0.001). The pattern of the chromosomal aberrations is constituted by chromatid bridges, complex aberrations, lagging, and vagrant chromosomes, while the abnormal metaphases are c-like metaphases, sticky metaphases, and metaphases with chromosomes expulsed from equatorial plate. The mitotic indices and the growth of the barley plantlets in the early ontogeny were stimulated by chromium. The changes induced in the frequency of division stages mainly consisted in prophase and telophase accumulation and diminution of metaphase and anaphase proportion.