A role for glutathione transferases functioning as glutathione peroxidases in resistance to multiple herbicides in black-grass

Plant J. 1999 May;18(3):285-92. doi: 10.1046/j.1365-313x.1999.00452.x.


Black-grass (Alopecurus myosuroides) is a major weed of wheat in Europe, with several populations having acquired resistance to multiple herbicides of differing modes of action. As compared with herbicide-susceptible black-grass, populations showing herbicide cross-resistance contained greatly elevated levels of a specific type I glutathione transferase (GST), termed AmGST2, but similar levels of a type III GST termed AmGST1. Following cloning and expression of the respective cDNAs, AmGST2 differed from AmGST1 in showing limited activity in detoxifying herbicides but high activities as a glutathione peroxidase (GPOX) capable of reducing organic hydroperoxides. In contrast to AmGST2, other GPOXs were not enhanced in the herbicide-resistant populations. Treatment with a range of herbicides used to control grass weeds in wheat resulted in increased levels of hydroperoxides in herbicide-susceptible populations but not in herbicide-resistant plants, consistent with AmGST2 functioning to prevent oxidative injury caused as a primary or secondary effect of herbicide action. Increased AmGST2 expression in black-grass was associated with partial tolerance to the peroxidizing herbicide paraquat. The selective enhancement of AmGST2 expression resulted from a constitutively high expression of the respective gene, which was activated in herbicide-susceptible black-grass in response to herbicide safeners, dehydration and chemical treatments imposing oxidative stress. Our results provide strong evidence that GSTs can contribute to resistance to multiple herbicides by playing a role in oxidative stress tolerance in addition to detoxifying herbicides by catalysing their conjugation with glutathione.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cloning, Molecular
  • Drug Resistance, Multiple
  • Gene Expression
  • Genes, Plant
  • Glutathione Peroxidase / genetics
  • Glutathione Peroxidase / metabolism*
  • Glutathione Transferase / genetics
  • Glutathione Transferase / metabolism*
  • Herbicides / pharmacology
  • Molecular Sequence Data
  • Oxidative Stress
  • Poaceae / drug effects
  • Poaceae / enzymology*
  • Poaceae / genetics
  • Sequence Homology, Amino Acid


  • Herbicides
  • Glutathione Peroxidase
  • Glutathione Transferase

Associated data

  • GENBANK/AJ010448
  • GENBANK/AJ010449
  • GENBANK/AJ010450
  • GENBANK/AJ010451
  • GENBANK/AJ010452
  • GENBANK/AJ010453
  • GENBANK/AJ010454
  • GENBANK/AJ010455