A Study Of Mechanisms By Which SOD1 Mimics Ehance Drought Tolerance Of Rice

In aerobic metabolism,plants produce a class of reactive oxygen species(ROS).This substance is lively with strong oxidizing ability.Under normal growth conditions,the ROS in the plant tissue is in a steady state,which is favorable for ROS as a second messenger to mediate multiple responses.When the plants are exposed to drought and high temperatures,the production of ROS increases rapidly and the internal steady state is destroyed.High concentration of ROS can cause serious damage to proteins and nucleic acids,eventually leading plant to death.Therefore,when plants are under stress,reducing the reactive oxygen species within the plant is conducive to plant survival.We synthesized four kinds of copper and zinc superoxide dismutase(SOD1)mimetic enzyme.The activity of SOD in the solution was determined by nitrogen blue tetrazolium(NBT)method.We used electron paramagnetic resonance(EPR),UV titration and X-ray single crystal diffraction and other methods to analyze the coordination structure of mimetic enzymes.The electrochemical curves show that the mimetic enzymes have reversible oxidation-reduction properties.We dyed the simulated enzyme into an aqueous solution,Compared with the control group,the content of ROS decreased and the activity of antioxidant enzymes increased.The level of SOD1 mRNA in rice tissue increased slightly,and the content of SOD protein in rice was higher than that in control group.CAT1 and APX1 mRNA levels were not changed,indicating that the addition of mimetic enzymes in the drought stress plays a role in regulating the level of reactive oxygen species and antioxidant enzymes,so that ROS content decreased.Fluorescence probe introduction method and kit method were used to detect the contents of Ca20and ABA in rice tissues.The results showed that the addition of ROS decreased and the content of ABA decreased slightly,but the accumulation of ABA was dependent on biosynthesis under drought stress and detachment from conjugate form.Therefore,the total ABA content was still increased.At the same time,the decrease of ROS content led to decrease the Ca2+ content in the roots,increase the Ca2+content and resulting in calcium oscillation.The results of the addition of mimetic enzyme were as follows.(1)the content of ROS decreased,(2)the total content of ABA increased,(3)resulting in calcium oscillation.These factors enhance the drought tolerance of rice.