Researches On Regulation Of Cadmium Accumulation And Transport By Ethylene In Arabidopsis Under Cadmium Stress

Heavy metal pollution has become an important work in national agendas. The repair of farmland polluted by heavy metal has started this year. In recent years, cadmium pollution has been an important problem in our daily life. The increase of cadmium content in national land is more than50%. In this study, we select Arabidopsis thaliana as materials to study whether ethylene regulates cadmium stress response in Arabidopsis thaliana under cadmium stress. And we deeply study ethylene how to regulate cadmium tolerance and ethylene signaling mechanisms under cadmium stress. This study not only provides theoretical basis for ethylene regulate cadmium stress response and improve plant resistance to heavy metal tolerance, but also has an important practical significance to heavy metal pollution problems and reducing the cadmium content in plants.In this paper, the mains results are as follows:1. When we added ethephon to ein2-5and Col-0under cadmium stress, ethephon alleviate the inhibition of growth effectively. It proved that endogenous ethylene could improve resistance to cadmium. Col-0and ein2-5could activate the mechanism of ethylene production under cadmium stress. It proved that ethylene could play a positive role for defense to resist to Cd stress.2. Lipid peroxidation is a very sensitive response caused by Cd stress. With the increase of Cd concentration, the content of MDA in leaves and roots of Arabidopsis seedling increased gradually, and had high consistency trend. Ethephon could make the content of MDA decrease. In the process of lipid catabolism, H2O2may be generated as products of fatty acid oxidation. Too much H2O2can cause oxidative damage to plants. With the increase of cadmium concentration, the content of H2O2in leaves of Arabidopsis seedling increased gradually, and had high consistency trend like MDA. It proved that exogenous ethylene can effectively reduce the production of H2O2under cadmium stress. It relieved lipid peroxidation caused by cadmium.3. With the increase of cadmium concentration, the cadmium content of aerial part and root increased. The content of cadmium treated in aerial parts and roots treated with ethephon had a decrease. Ethylene could reduce the cadmium translocation factor of Arabidopsis seedlings. It makes more cadmium accumulated in roots and alleviates cadmium accumulated in shoots. Ethylene mainly improves AtATM3gene expression to make an effort.4. CAT and APX activity in Arabidopsis seedlings showed decrease with the increased of cadmium concentration. When adding ethephon, CAT and APX activity restored. POD and SOD activity in Arabidopsis seedlings showed increased and then decreased with the increase of cadmium concentration. When adding ethephon, POD and SOD activity showed decreased. GR activity in Arabidopsis seedlings showed increased with the increase of cadmium concentration. When adding ethephon, GR activity decreased.5. GR gene expression level in ein2-5is higher than Col-0under cadmium stress. It proved that ethylene can inhibit the formation of GSH to impact phytochelatins. After addition of ethephon, the decrease of GR gene expression makes GSH decrease. Under cadmium stress, ein2-5became more senescent than Col-0. After adding ethephon, SAG21gene expression in ein2-5and Col-0showed increased significantly. It proved that ethylene promoted to be senile.