Enantioselectivity of herbicide imazapyr to Arabidopsis thaliana and Daphnia pulex
| Autor: | Yu-Ling Hsiao, 蕭鈺齡 |
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| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 In this study, the effects of mobile phase composition and flow rate on separation efficiency were investigated and the enantiomers were also collected to study the enantioselectivity of imazapyr to Arabidopsis thaliana. Successful enantiomeric separation of imidazolinone herbicides by high-performance liquid chromatography (HPLC) equipped with Chiralcel OJ-H column was performed. Imazapyr, one of the imidazolinone herbicides, was analyzed. The pure enantiomers of imazapyr could be obtained by HPLC with mobile phase of n-hexane/2-propanol at 85/15 (v/v) and flow rate at 1.5 mL/min. The separated enantiomers were determined by HPLC, GC-MS, circular dichroism spectropolarimeter and polarimeter. The purity of these eanatiomers were 95 % and 99 %. The selective effects of the enantiomers of imazapyr on wild type A. thaliana were investigated. The two enantiomers and the racemate had significantly different effects on A. thaliana. After treated with herbicides at the same concentration, significant effect on external appearance showed in the (R,+)-imazapyr treatment, and the higher the concentration treated, the more adverse effects were showed. The chlorophyll content revealed the same trend. The (S,-)-imazapyr treatment has lower proline content than the other treatments and the (R,+)-isomer treatment has the highest proline content. The MDA content of the (R,+)-imazapyr treatment was also higher than other two treatments significantly. Additional, the inhibition of acetolactate synthase from A. thaliana (wtALS) was also enantioselective. (R,+)-imazapyr inhibited the activity of wtALS around 83%. (S,-)-isomer and racemate inhibited the activity of wtALS about 20 and 53%, respectively. Moreover, the effects of imazapyr and its enantiomers on mutant A. thaliana GH90 were significant whether in appearance, physiological indices or antioxidant enzymes. (S,-)-Imazapyr shows less stress then rac- and (R,+)-imazapyr. The inhibition rate of ALS extracted from mutant A. thaliana GH90 (mALS) shown that (R,+)-imazapyr inhibited the activity about 20%, and (S,-)-isomer was nearly no inhibition ability. As the result, it reveals that the enantiomers of imazapyr had selective effects on A. thaliana both wild type and mutant. It reveals that there are unfavorable contacts between wtALS and (S,-)-imazapyr by simulation of the wtALS-imazapyr binding complex. The point mutation of mALS just blocked the channel leading to the binding site and that cause the resistance. On the other hand, (R,+)-imazapyr shows more favorable to bind to the second binding site of mALS than (S,-)-imazapyr. That explains the enantioselective of imazapyr toward imazapyr-resistant A. thaliana GH90. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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