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Vacuolar Glyphosate-Sequestration Correlates with Glyphosate Resistance in Ryegrass (Lolium spp.) from Australia, South America, and Europe: A 31P NMR Investigation
journal contribution
posted on 2012-02-08, 00:00 authored by Xia Ge, D. André d’Avignon, Joseph J. H. Ackerman, Alberto Collavo, Maurizio Sattin, Elizabeth
L. Ostrander, Erin L. Hall, R. Douglas Sammons, Christopher PrestonLolium spp., ryegrass,
variants
from Australia, Brazil, Chile, and Italy showing differing levels
of glyphosate resistance were examined by 31P NMR. Extents
of glyphosate (i) resistance (LD50), (ii) inhibition of
5-enopyruvyl-shikimate-3-phosphate synthase (EPSPS) activity (IC50), and (iii) translocation were quantified for glyphosate-resistant
(GR) and glyphosate-sensitive (GS) Lolium multiflorum Lam. variants from Chile and Brazil. For comparison, LD50 and IC50 data for Lolium rigidum Gaudin variants from Italy were also analyzed. All variants showed
similar cellular uptake of glyphosate by 31P NMR. All GR variants showed glyphosate
sequestration within the cell vacuole, whereas there was minimal or
no vacuole sequestration in the GS variants. The extent of vacuole
sequestration correlated qualitatively with the level of resistance.
Previous 31P NMR studies of horseweed (Conyza
canadensis (L.) Cronquist) revealed that glyphosate
sequestration imparted glyphosate resistance. Data presented herein
suggest that glyphosate vacuolar sequestration is strongly contributing,
if not the major contributing, resistance mechanism in ryegrass as
well.