Enantioselectivity in the phytotoxicity of herbicide imazethapyr.
Enantioselectivity in the phytotoxicity of herbicide imazethapyr.
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DOI：
10.1021/jf803673e
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发表时间：
2009-01
影响因子：
6.1
通讯作者：
Qingyan Zhou;Chao Xu;Yong-song Zhang;Weiping Liu
中科院分区：
文献类型：
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作者：
Qingyan Zhou;Chao Xu;Yong-song Zhang;Weiping Liu
手性化合物在植物生化过程中通常表现出对映选择性。随着手性除草剂应用的日益广泛，其对映体选择性的植物毒性值得进一步研究，但目前这方面的研究资料很少。研究了除草剂咪唑乙烟酸（imazethapyr，IM）对玉米（Zea mays L.）幼苗用高效液相色谱法分离了IM的对映异构体，根据八分体法则确定了它们的绝对构型为S-（+）-IM和R-（-）-IM。植物生长的测量和形态，显微镜下，超微结构的观察后进行处理与个别IM对映异构体和外消旋体。根系形态观察表明，根直径显著增加，而根体积、表面积和根尖数显著减少。IM对映体选择性地破坏根毛生长，并显着减少边缘细胞从尖端脱落。IM也对玉米根中的细胞器，如平衡细胞、线粒体、网状体和内质网产生不利影响。此外，IM处理后细胞膜和细胞壁比平时厚。结果表明，R-（-）-IM对玉米幼苗根系生长的影响大于S-（+）-IM。（+/-）-IM的抑制作用介于S-（+）-和R-（-）-IM之间。活性对映体的行为，而不仅仅是外消旋体，可能与IM的除草效果和生态安全性更相关。因此，在评价除草剂IM的生物利用度时，应考虑对映体的差异。
Chiral compounds usually behave enantioselectively in phyto-biochemical processes. With the increasing application of chiral herbicides, their enantioselective phytotoxicity to plants merits further study, and little information is available in this area. The purpose of this study was to examine the enantioselective phytotoxicity of the herbicide imazethapyr (IM) on the roots of maize (Zea mays L.) seedlings. Enantiomers of IM were separated by HPLC, and their absolute configurations were confirmed as S-(+)-IM and R-(-)-IM by the octant rule. Plant growth measurements and morphological, microscopic, and ultrastructural observations were conducted after treatment with individual IM enantiomers and the racemate. Observations of root morphology showed that the root diameter significantly increased, whereas the root volume, surface area, and number of root tips decreased significantly. IM enantiomers selectively damaged root hair growth and significantly reduced the sloughing of border cells from the tips. IM also had adverse effects on cell organelles, such as statocytes, mitochondria, dictyosomes, and endoplasmic reticulum in maize roots. Moreover, cell membranes and cell walls were thicker than usual after IM treatment. All of the results showed the same trend that the R-(-)-IM affected the root growth of maize seedlings more severely than the S-(+)-IM. The inhibition abilities of (+/-)-IM was between S-(+)- and R-(-)-IM. The behavior of the active enantiomer, instead of just the racemate, may have more relevance to the herbicidal effects and ecological safety of IM. Therefore, enantiomeric differences should be considered when evaluating the bioavailability of the herbicide IM.