Effects Of Selenium On DNA Damage Of Root Tip Cells Of Vicia Faba Under The Stress Of Cadmium

Selenium is an essential micronutrient. It is well known that selenium plays many roles, such as, it appears to be a key nutrient in resisting oxidation and senescence, strengthening the function of the immuno-system, and preventing cardiovascular disease. Especially in the past few years, the relationship between selenium and heavy metal has become the great interest of people. The comet assay, also known as the single cell gelelectro Phoresis (SCGE) assay,is a rapidly and highly sensitive technique of measuring DNA breakage in individual cells. The technique has a wide range of applications due to its unique advantages such as quickness highsensitivity,and small sample requirement. This sutdy aims to establish SCGE technique to detect the cellular DNA damage of root tip cells of Vicia faba caused by Cadmium and Selenium, furthermore to employ this technique to study DNA damages of root tip cells of Vicia faba under the stress of Selenium and Cadmium compound.The results showed when Vicia faba were cultivated in different concentrations of Cadmium ,DNA damage of root tip cells of Vicia faba changed from increase to decline with the increasing of cadmium concentrations. SCGE showed that DNA damage of root tip cells of Vicia faba in each Cd exposed group were more serious than that of control group with statisical significance(P<0.05).The study on DNA damage of cells showed, when the concentrations of Se⁴⁺ was below 0.5μmol/L, DNA damage decreased with the increasing of Se⁴⁺ concentration and poisoned time, but when the concentration of Se⁴⁺ was above 5μmol/L, DNA damage increased. When the concentration of Se in the combined concentrations of Se and Cd was below 5μmol/L, DNA damage declined with the increasing of Se concentration and poisoned time, but when the concentration was above 5μmol/L, DNA damage rose. The DNA damage of five doses of selenium was lower significantly than that of the positive control, furthermore, the extent of DNA damage of Group medium dose of selenium (5μmol/L) was lower than the other groups.Within low concentrations, Se relieved the DNA damage of plants under Cd stress and enhanced the resistance of plants. But if the concentrations of Se exceeded a certain range, the damage would be severe.