The Cytotoxicity Of Aqueous Extraction From Trifolium Repens L. On Root Tip Cell Of Vicia Faba

Trifolium repens L, native to the Mediterranean, has become a major invasive plant growing in temperate, sub-tropical as well as high altitude areas. In China, T. repens has spread extremely rapidly, now it can be found in Heilongjiang, Jilin, Liaoling, Xinjiang, Sichuan and Yunnan Provinces. Knowledge of the mechanisms why plants can successfully invade and disperse fastly is very useful in determining the invasive mechanism of this plant.In this paper the cytotoxicity of aqueous extraction from T. repens L. on root-tip cells of Vicia faba was investigated by using micronucleus assay and chromosome aberration assay. The results showed that the aqueous extracts of T. repens produced cytotoxicity and inhibited mitosis of V. faba root tip cells. With the increase of concentration and action time, mitotic indexes decreased and frequencies of micronucleus increased. There were some abnormal phenomenon of root tip cells such as micronucleus, chromosome bridge, chromosome break, chromosome lag, chromosome conglutination and three pole divide.In this study, by using artificial control soil water and temperature, the activities of antioxidant enzymes, which are crucial in plant's defense against stresses, were studied in T. repens by various environments stresses. These results indicated that this species could adapt to its environment since it has wider range of tolerance on temperature and a certain level of drought. Then we chose three temperatures (5℃, 25℃and 35℃) to treat T. repens and studied the toxic effects of T. repens under different temperature stress. The results indicated that the cytotoxicity of aqueous extraction from T. repens changed because of temperature stresses, the solution inhibited mitotic indexes a greater degree, increased frequencies of micronucleus and chromosome aberration. The effects of three aqueous extraction on the Super Oxide Dismutase were investigated., the analysis of SOD isoenzymes revealed that the number of SOD isoenzyme were unchanged ,but compare to control the activities of SOD decreased and the content of MDA increased. The comprehensive analysis showed that the general cytotoxicity of the low temperature group (5℃) was strongest, high temperature group (35℃) was second, normal temperature(25℃)was smallest. A Preliminary analysis of allelochemical showed there were plenty of o-hydroxybenzene and m-hydroxybenzene in T. repens. Treated by temperature, the content of hydroxybezen increased which was probably that temperature stress changed and increased the secondary metabolism material of T. repens, finally increased cytotoxicity of the aqueous extracts of this plant.