Investigating the mechanisms of glyphosate resistance in Lolium multiflorum

Journal or Publishing Institution: Planta

Study: http://link.springer.com/article/10.1007%2Fs00425-007-0490-6

Author(s): Perez-Jones, A., Park, K.W., Polge, N., Colquhoun, J. and Mallory-Smith, C.A.

Article Type: Peer Reviewed Study

Record ID: 1880

Abstract: Evolved resistance to the herbicide glyphosate has been reported in eleven weed species, including Lolium multiflorum. Two glyphosate-resistant L. multiflorum populations were collected, one from Chile (SF) and one from Oregon, USA (OR), and the mechanisms conferring glyphosate resistance were studied. Based on a Petri dish dose–response bioassay, the OR and the SF populations were two and fivefold more resistant to glyphosate when compared to the susceptible (S) population, respectively; however, based on a whole-plant dose–response bioassay, both OR and SF populations were fivefold more resistant to glyphosate than the S population, implying that different resistance mechanisms might be involved. The S population accumulated two and three times more shikimic acid in leaf tissue 96 h after glyphosate application than the resistant OR and SF populations, respectively. There were no differences between the S and the glyphosate-resistant OR and SF populations in ¹⁴C-glyphosate leaf uptake; however, the patterns of ¹⁴C-glyphosate translocation were significantly different. In the OR population, a greater percentage of ¹⁴C-glyphosate absorbed by the plant moved distal to the treated section and accumulated in the tip of the treated leaf. In contrast, in the S and in the SF populations, a greater percentage of ¹⁴C-glyphosate moved to non-treated leaves and the stem. cDNA sequence analysis of the EPSP synthase gene indicated that the glyphosate-resistant SF population has a proline 106 to serine amino acid substitution. Here, we report that glyphosate resistance in L. multiflorum is conferred by two different mechanisms, limited translocation (nontarget site-based) and mutation of the EPSP synthase gene (target site-based).

Keywords: Glyphosate Resistance, Lolium multiflorum, Translocation, EPSP Synthase, Shikimic Acid; 3-phosphoshikimate 1-carboxyvinyltransferase, Amino Acid Substitution, Bioassays, Complementary DNA, Dose Response, Genes, Glyphosate, Herbicide Resistance, Leaves, Nucleotide Sequences, Proline, Resistance Mechanisms, Sequence Analysis, Serine, Weeds, Chile, Oregon; Amino Acid Sequence, Base Sequence, Biological Transport, Drug Dose-Response Relationship, Glycine, Herbicide Resistance, Herbicides, Lolium, Molecular Sequence Data, Plant Leaves, Sequence Alignment, DNA Sequence Analysis,

Citation: Perez-Jones, A., Park, K.W., Polge, N., Colquhoun, J. and Mallory-Smith, C.A., 2007. Investigating the mechanisms of glyphosate resistance in Lolium multiflorum. Planta, 226(2), pp.395-404.