Basis for Differential Chemical Selectivity of MG-191 Safener against Acetochlor and EPTC Injury to Maize

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The influence of MG-191 safener on the uptake, translocation and metabolism of [14C]acetochlor and [,4C]EPTC was studied. The amounts of absorbed radioactivity by maize seedlings at 3, 6, 24, and 72 h after applications of [14C]labeled herbicides and [I4C]MG-191 were different. Plants treated with [l4C]acetochlor took up 30- to 50-fold more radiolabel within 72 h than [14C]EPTC- or [14C]MG-191-treated plants. Addition of MG-191 caused only minor changes in the rate of herbicide absorption. EPTC and MG-191 and/or their metabolites moved quickly acropetally and partitioned equally between root and shoot tissues up to 72 h. The amount of acetochlor and/or its labeled metabolites translocated to shoot tissues was less than 10%. MG-191 practically had no influence on herbicide translocation rates. With all chemicals the amounts of water-soluble and unextractable fractions increased while the ratio of hexane-extractable metabolites decreased with time. TLC analyses of both water- and hexane-soluble metabolites confirmed the fast metabolism of acetochlor. The acetochlor metabolism took place via GSH conjugation and more polar, non-conjugated metabolites compared to parent molecule were detected in hexane-soluble fraction. MG-191 enhanced acetochlor metabolism by decreasing the portion of non-metabolized acetochlor. EPTC metabolism resulted in water-soluble metabolites having similar chromatographic properties to those of acetochlor. However, there was no safener effect on non-metabolized EPTC content of plants. It appears that MG-191 protects maize against EPTC by enhancing the early rate of conjugation with GSH after initial oxidative metabolism.

Original languageEnglish
Pages (from-to)836-845
Number of pages10
JournalZeitschrift fur naturforschung - section c journal of biosciences
Issue number9-10
Publication statusPublished - Oct 1 1991


  • Acetochlor
  • Chemical Selectivity
  • EPTC
  • MG-191
  • Metabolism
  • Safener
  • Translocation
  • Uptake

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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