Genotoxic Effects of Nickel on Root Tip Cells of Vicia faba L.

Nickel is one ofthe most toxic environmental pollutants affectinggeneticallythe various organisms. In order toevaluate the genotoxicity of nickel and the feasibility of nickel pollution detection by Vicia faba-micronucleus test, we examined the growth, mitotic index, rate of micronuclei formation and chromosome aberrations in root tip cells of Vicia faba L. after exposure to different concentrations of nickel nitrate rangingfrom5 to 5 000 μmol·L-1. The results showed that nickel enhanced significantly the growth of root tip cells and mitotic index, but had noevident effects on the formation ofmicronuclei and chromosome aberrations at lowconcentration of5 μmol·L-1. However, higher concentra- tions of10￣5 000 μmol·L-1 nickel decreased the growth ofroot tip cells and mitotic indexwith significant dose- effect relationship. The rate of micronuclei and chromosome aberrations was increased dose-dependently, reaching the maximum values at 100 μmol·L-1 and 50 μmol·L-1, respectively, followed bya drop with the increase ofnickel concentrations, however, both higher than those of the control. Fragmental and lagging chromosomes were predominant in chromosome aberrations caused bynickel. These results indicate that nickel exerts genotoxicitytoroot tip cells ofVicia faba L. toa certain degree, as shown bymicronucleus formation and chromosome aberrations. The results alsoindicate that Vi-cia faba-micronucleus test is feasible for detection ofnickel pollution in environment at certain concentrations rangingfrom5 to500μmol·L-1.