β-六溴环十二烷对玉米生长代谢的对映体选择性影响

Enantioselective effects ofβ-HBCD on the growth metabolism of maize

为了探讨不同光旋纯活性的β-HBCD对植物生长代谢的对映体选择性影响,本研究采用高效液相色谱法(HPLC)优化分离并制备得到β-六溴环十二烷(β-HBCD)单一对映体((+)β-HBCD和(−)β-HBCD),开展了不同浓度梯度的(+)、(rac)和(−)β-HBCD溶液对玉米幼苗的水培暴露实验。随着β-HBCD暴露浓度的增加,玉米体内超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性(除(−)β-HBCD处理外)、以及花青素含量均呈现显著的先增加后减少的趋势,表明β-HBCD诱发了玉米机体的抗氧化酶系统和非酶系统的应激反应,其中(+)β-HBCD诱导SOD、APX活性和花青素水平增加量最大,在玉米根部分别达到空白对照组的1.85、5.26、3.55倍,(−)β-HBCD处理增加量最小,分别达到空白对照组的1.63、3.90、2.28倍;玉米体内的活性氧(ROS)平衡被破坏,超氧阴离子(O2⋅−)水平被显著诱导,诱导量为(+)β-HBCD>(rac)β-HBCD>(−)β-HBCD;幼苗根系活力受到显著的抑制,(+)、(rac)和(−)β-HBCD处理组的抑制量均在最高暴露浓度时达到最大,分别较空白对照组减少了65.1%、39.7%和28.5%,推测O2⋅−水平失衡,根系活力下降,是导致植物生长代谢受阻的重要影响因素。综上所有证据表明β-HBCD对玉米的生长代谢产生了对映体选择性影响,毒性顺序为(+)β-HBCD>(rac)β-HBCD>(−)β-HBCD。本研究对综合评价HBCD的环境行为和生态风险具有重要意义。

In order to explore the enantioselective effects of β-HBCD with different optical activity on plant growth metabolism,the optimized separation and preparation of(+) β-HBCD and(-) β-HBCD were performed by high performance liquid chromatography(HPLC).Hydroponic O·-2 O·-2 exposure experiments of maize seedlings were conducted at solutions of(+),(rac) and(-) β-HBCDs with different concentrations.The activities of superoxide dismutase(SOD) and ascorbate peroxidase(APX)(except for(-) β-HBCD treatments) and anthocyanin content in maize increased significantly at first and then decreased with the increasing exposure concentrations of β-HBCD,indicating thatβ-HBCD induced stress response of antioxidant enzyme system and non-enzymatic system in maize.The strongest induced effects on SOD,APX activity and anthocyanin level were found in(+) β-HBCD treatments,which reached 1.85,5.26 and 3.55 times higher than blank control group in maize roots,respectively.The induced effects of(-) β-HBCD treatments were the smallest,reaching 1.63,3.90 and 2.28 times higher than blank control group,respectively.The ROS balance in maize was destroyed,and O;level was significantly induced in the order of(+) β-HBCD >(rac) β-HBCD >(-) β-HBCD.The root activity of seedlings was significantly inhibited,and the maximum inhibition reached at the highest exposure concentration treatment,which decreased by 65.1%,39.7% and 28.5%,respectively,compared with blank control group for(+),(rac) and(-) β-HBCD treatments.It is speculated that the imbalance of O;level and the decrease of root activity are the important factors that affect the growth and metabolism of plants.All the results demonstrated the significant enantioselective effects of β-HBCD on maize growth and metabolism with the toxicity order of(+) β-HBCD >(rac) β-HBCD >(-) β-HBCD.This study is of great significance for comprehensive assessment of the environmental behavior and ecological risk of HBCD.