DNA analysis of herbarium Specimens of the grass weed Alopecurus myosuroides reveals herbicide resistance pre-dated herbicides

PLoS One. 2013 Oct 16;8(10):e75117. doi: 10.1371/journal.pone.0075117. eCollection 2013.


Acetyl-CoA carboxylase (ACCase) alleles carrying one point mutation that confers resistance to herbicides have been identified in arable grass weed populations where resistance has evolved under the selective pressure of herbicides. In an effort to determine whether herbicide resistance evolves from newly arisen mutations or from standing genetic variation in weed populations, we used herbarium specimens of the grass weed Alopecurus myosuroides to seek mutant ACCase alleles carrying an isoleucine-to-leucine substitution at codon 1781 that endows herbicide resistance. These specimens had been collected between 1788 and 1975, i.e., prior to the commercial release of herbicides inhibiting ACCase. Among the 734 specimens investigated, 685 yielded DNA suitable for PCR. Genotyping the ACCase locus using the derived Cleaved Amplified Polymorphic Sequence (dCAPS) technique identified one heterozygous mutant specimen that had been collected in 1888. Occurrence of a mutant codon encoding a leucine residue at codon 1781 at the heterozygous state was confirmed in this specimen by sequencing, clearly demonstrating that resistance to herbicides can pre-date herbicides in weeds. We conclude that point mutations endowing resistance to herbicides without having associated deleterious pleiotropic effects can be present in weed populations as part of their standing genetic variation, in frequencies higher than the mutation frequency, thereby facilitating their subsequent selection by herbicide applications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetyl-CoA Carboxylase / genetics*
  • Alleles
  • Amino Acid Substitution
  • Biological Specimen Banks
  • DNA, Plant / genetics*
  • Gene Frequency
  • Genotyping Techniques
  • Herbicide Resistance / genetics*
  • Herbicides / pharmacology
  • Isoleucine / genetics
  • Leucine / genetics
  • Mutation
  • Plant Proteins / genetics*
  • Plant Weeds / drug effects
  • Plant Weeds / genetics*
  • Poaceae / drug effects
  • Poaceae / genetics*
  • Time Factors


  • DNA, Plant
  • Herbicides
  • Plant Proteins
  • Isoleucine
  • Acetyl-CoA Carboxylase
  • Leucine

Grants and funding

The authors are grateful to Bayer CropScience SA (Lyon, France) for supporting this work. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.