| Hexabromocyclododecane（HBCD）is currently one of the most produced brominated flame retardants.It has been banned by many countries due to its universal persistent organic pollution characteristics,but its existence in the environment and its harm to organisms still cannot be ignored.In this study,high performance liquid chromatography（HPLC）was used to separate and prepare the three enantiomers of HBCD.Maize were the test crop,which were cultivated by the method of water culture.Maize seedlings were cultured under exposure gradients of 0.5,1.0,2.0,3.0 and 5.0μg·L-1.Random amplified polymorphic DNA（RAPD）was used to detect gene stability in maize,the hyperchromic effect was used to determine the type of gene damage in maize,and the difference in expression of different superoxide dismutase（SOD）genes was detected by fluorescent quantitative PCR.Research on HBCD’s genetic damage to maize seedlings was carried out,the main results are as follows:1)After 72 hours of HBCD exposure culture,the DNA stability in maize was significantly affected.The toxicity of（rac）α-HBCD is higher than（rac）β-HBCD,and（rac）γ-HBCD is the weakest;The toxicity of（+）configuration is significantly higher than that of（-）configuration;The damage to root genes is higher than the ground parts.2)After 72 hours of exposure to different isomers and enantiomers of HBCD.DNA presents different degrees of cross-linking damage and breaking damage,and the damage to the roots is higher than that of the other parts.Forα-HBCD andγ-HBCD,（+）configuration is more toxic than（-）configuration on DNA damage to the maize.（-）β-HBCD is more toxic to the stems and leaves than（+）β-HBCD,but the damage to root DNA is less than（+）β-HBCD.3)72 h HBCD exposure culture affected the expression of SOD genes in maize,among whichα-HBCD andβ-HBCD mainly affect the expression of Cu/Zn-SOD genes located in the cytoplasm and Fe-SOD genes located in the chloroplast;Compared with the previous two isomer,γ-HBCD has a more obvious effect on the expression of Mn-SOD gene located in mitochondria.The overall order of toxicity isα-HBCD>β-HBCD>γ-HBCD.Between different enantiomers:（+）α-HBCD has a higher effect on gene expression in maize than（-）α-HBCD.（+）β-HBCD has more significant effects on root Cu/Zn-SOD,Fe-SOD,Mn-SOD and above-ground Cu/Zn-SOD gene expression,while（-）β-HBCD has more significant effects on the expression of above-ground Fe-SOD gene and Mn-SOD gene.（+）γ-HBCD enantiomers affect the expression of Cu/Zn-SOD and Mn-SOD genes in maize more obviously,while（-）γ-HBCD has a greater impact on Fe-SOD in maize. |
