The Mechanism Of Cadmium Damage In Saccharomyces Cerevisiae And Plant

Cadmium（Cd） is one of the major pollutants, so in order to provide the theory basis forthe pollution control become more important. In this paper, Saccharomyces cerevisiae/Zeamays（Zhengdan958）/rice（Zhengdao18） were used as experimental material in research on thetoxicity action mechanism of Cd.The result showed that: ROS content increased significantly in Cd-stressedSaccharomyces cerevisiae cells, with decreased of cells activity, and all the results above wereconcentration dependently. Moreover Cd treatment could decrease the activities ofSOD/CAT/GP, and reduced glutathione（GSH） content was decreased significantly, and MDAcontent increased.We used Exogenous n-acetylcysteine（NAC） treated Cd-stressedSaccharomyces cerevisiae, and found that NAC reduced the level of ROS, increased cellsactivity, SOD/CAT/GP activities and GSH content, with MDA content decreased. Thisindicates that the detoxication of NAC to Cd stress by increasing the antioxidase activities.Then, this study describes involvement of superoxide anion and hydrogen peroxide inthe germination and early development of cadmium stressed Zea mays/rice seeds respectively.The following indexes were determined: germination rate, early growth, superoxide anion（O₂·-） and hydrogen peroxide （H₂O₂） content, NADPH oxidase activity and distribution, MDAcontent （peroxidative decomposition product malondialdehyde）. The results obtained were asfollows: Low concentration of cadmium could improve the germination rate of Zea mays,whereas inhibite the germination rate of rice. When both of the seeds were exposed to0.2mMCdCl2for6days respectively, significant decrease of O₂·-content were observed, seedlingsgrowth were inhibited significantly. During this process, the activity of NADPH oxidasedecreased in Zea mays, but increased in rice. MDA content reduced as well. Exogenous O₂·-produced by generating system significant reversed the early growth of Cd-stressed seedlings.Showed that Cd caused the inhibition of the early growth in Zea mays and rice by increasingO₂·-. But the mechanisms were different in Zea mays and rice. It should through reducing theactivity of NADPH oxidase to inhbite O₂·-production in Zea mays, however throughincreasing the antioxidase activities to decrease O₂·-.The results show that Cd induced induced oxidative stress by increasing ROS content,caused oxidative damage and cell death in Saccharomyces cerevisiae. However Cd stresscaused seedlings growth inhibition in plant may through decreasing of O₂·-content.