| As a new kind of persistent inorganic pollutants,perchlorate has characteristics such as fast proliferation,difficult to degradation and high water solubility.Surveys show that exposure to perchlorate is common for human,and the main sources are water and food.Perchlorate ions(ClO4-)have similar ion diameters with iodide ions,which can inhibit the absorption of iodine and weaken the thyroid function,causing metabolic disorders.In order to explore the effects of perchlorate on plant and understand the regulating effect of exogenous Salicylic acid(SA)on the plant physiological response to perchlorate stress,Helianthus tuberosus L.was chosen as the experimental material under the controlled conditions.The main results are as follows:1.Helianthus tuberosus L.from Xuzhou,Weifang,Nanjing was taken as the experimental material after filtering by NaCl stress.And under the NaClO4 treatment,results of tuber germination showed that the different concentration of ClO4-between treatments has certain difference,and the germination of Helianthus tuberosus L.was declined as the rise of concentration.At low concentration,the trend had been obvious,and the rate of Nanjing was largest,reflecting the poor tolerance to perchlorate.The results also show that the germination time of Helianthus tuberosus L.under ClO4-.was generally delayed.2.After setting NaCl treatment groups to eliminate the disturb from Na+ of NaClO4,a solution experiment was conducted to study the effects of ClO4-stress on root system,antioxidant enzyme system,soluble sugar,MDA,Pro,leaf SPAD and other fluorescenceparameters of these three Helianthus tuberosus L..The result showed that the growth of three Helianthus tuberosus L.was inhibited to some extent under ClO4-treatment.At low concentrations,their contents of SPAD,Fv/Fm,ETR were higher than those of control groups and NaCl treatment groups.But the variation of the root vigor,SOD,POD and CAT were different between three Helianthus tuberosus L.And at low concentrations,trends of the contents of soluble sugar and MDA were shown opposite with other indexes.Compared with the root,the indexes of leaves system had a greater difference between the NaClO4 treatment groups and the NaCl treatment group,which indicated that the damage to the leaves of Helianthus tuberosus L.was more distinct than that on the root.3.The effects of different exogenous SA treatments on the growth physiology and fluorescence parameters of three species of Helianthus tuberosus L.under perchlorate stress were studied.The results showed that the application of 50μmol·L-1 SA could alleviate the damage of leaves and roots of Helianthus tuberosus L..T3 groups did the best,effectively alleviating the damage of Helianthus tuberosus L.by activating antioxidant enzymes and photosynthesis.Spraying SA has the greatest influence on ETR、qP、qN of Helianthus tuberosus L.by gray correlation analysis.4.The DNA damage of Helianthus tuberosus L.under ClO4-was studied by using single cell gel electrophoresis(SCGE).It was found that the DNA mobilization rate of NaClO4 treatment group was significantly higher than that of the control group.The migration distance of Helianthus tuberosus L.cells was gradually augmented with increasing concentration of ClO4-.Further analysis of the cell damage(Olive Tail Moment,OTM)determined by CASP software showed that the OTM values of the three Helianthus tuberosus L.rooted cells were not significantly different under low concentration,and tailing in the comet electrophoresis picture was shorter.At the medium concentration,the OTM values of the Xuzhou Helianthus tuberosus L.were significantly increased much more than other two materials(Weifang and Nanjing),and the comet electrophoresis images showed obvious tailing.But at high concentration,all of the three Helianthus tuberosus L.appeared smearing phenomenon,and the OTM of Weifang and Nanjing was higher than that of Xuzhou.So it was presumed that the genotoxicity and oxidative stress to Xuzhou Helianthus tuberosus L.were relatively higher. |
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