Effects Of Cu Zn Treatment To Seed Germination And Physiological And Biochemical Characteristics In Wheat Roots

Heavy metal had effect on the growth and the physiological activity of crops when in soil.Therefore,the research of crops growth and the physiological changes under heavy metal treatment has profound effect.Used the spring wheat(Triticum aestivum L,cv Longchun 30)as experimental material to study the effects of different concentrations of Cu Cl2 and Zn Cl2 to seed germination,seedling growth,reactive oxygen and ascorbate-glutathione cycle.The purpose of this study was to reveal the toxic effects of plants caused by Cu Zn treatment and the response mechanism of As A-GSH cycle in plants under heavy metal treatment.The main results are as follows:1.The wheat roots were inhibited with different concentrations of Cu treatment,while the seed germination and plant growth was inhibited significantly in high Cu concentration.All concentration of Zn did not affect the seed germination,the growth of wheat roots and shoots were inhibited by high Zn concentration.Total chlorophyll and chlorophyll a contents are not significantly affected under Cu Zn stress.The content of chlorophyll b was significantly decreased and the ratio of chlorophyll a/b was significantly increased by high Cu Zn concentration.Indicated that chlorophyll b is more sensitive to Cu / Zn than chlorophyll a.2.The contents of hydroxyl radical(�OH)and hydrogen peroxide(H2O2)in wheat roots are significantly increased under different Cu Zn concentrations.the accumulation of ROS in the roots increased the degree of lipid peroxidation,which resulted in the increase of malondialdehyde(MDA)content in the membrane lipid peroxidation product.3.The activity of superoxide dismutase(SOD)was activated and the activity of peroxidase(POD)increased first and then decreased and the activity of catalase(CAT)was significantly inhibited in high Cu concentration.SOD activity was inhibited under low Zn concentration and POD activity was inhibited under all Zn treatments and CAT activity was inhibited under high Zn treatment.Resulting that ROS contents increased in high Cu Zn concentrations and the growth of wheat was affected.4.The contents of total ascorbic acid,As A,DHA,GSH and GSSG in wheat roots were significantly increased under different Cu Zn concentrations.The ratio of As A/DHA increased under high Cu Zn treatment and the ratio of GSH/GSSG decreased after Cu treatment,while the ratio of GSH/GSSG increased first then down in all Zn treatments.The results showed that the content of antioxidant in wheat was increased by Cu Zn treatment and the ability of toleratance heavy metal was enhanced.5.The activities of ascorbate peroxidase(APX),glutathione reductase(GR)and dehydroascorbate reductase(DHAR)in wheat roots were observed under different Cu concentrations for the enhanced trend.The activity of APX was significantly higher under high Zn concentration and the activities of GR,DHAR were increasing under different Zn treatment.AAO activity was activated by high Cu Zn treatment.The activity of MDHAR decreased gradually under different Cu Zn concentrations.Increased APX activity facilitates the removal of H2O2 and slows its damage to wheat,which increases GR activity ensures the accumulation of GSH and the regeneration of As A was associated with increased DHAR activity.The results show that: The effect of heavy metal Cu Zn treatment on seed germination,root and plants growth and chlorophyll content was different impact and plants growth were inhibited was related to the accumulation of ROS.The accumulation of ROS were related to increased SOD activity and POD activity and decreased CAT activity under Cu treatment,which the decreased of POD activity and CAT activity under Zn treatment.The increase of antioxidant(As A,DHA,GSH and GSSG)and the enhanced activity of APX,GR,AAO and DHAR maintained the high efficiency of As A-GSH cycle,enhanced the tolerance ability of heavy metal as well as remitted oxidative damage by ROS caused.