EPSPS gene amplification conferring resistance to glyphosate in windmill grass (Chloris truncata) in Australia.
BACKGROUND
Five glyphosate-resistant populations of Chloris truncata originally collected from New South Wales were compared with one susceptible (S) population from South Australia to confirm glyphosate resistance and elucidate possible mechanisms of resistance.


RESULTS
Based on the amounts of glyphosate required to kill 50% of treated plants (LD50), glyphosate resistance (GR) was confirmed in five populations of C. truncata (A536, A528, T27, A534 and A535.1). GR plants were 2.4-8.7-fold more resistant and accumulated less shikimate after glyphosate treatment than S plants. There was no difference in glyphosate absorption and translocation between GR and S plants. The EPSPS gene did not contain any point mutation that had previously been associated with resistance to glyphosate. The resistant plants (A528 and A536) contained up to 32-48 more copies of the EPSPS gene than the susceptible plants.


CONCLUSIONS
This study has identified EPSPS gene amplification contributing to glyphosate resistance in C. truncata. In addition, a Glu-91-Ala mutation within EPSPS was identified that may contribute to glyphosate resistance in this species. © 2017 Society of Chemical Industry.
School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia.
The D
TD
Ngo
School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia.
Jenna M
JM
Malone
School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia.
Peter
P
Boutsalis
School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia.
Gurjeet
G
Gill
School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia.
Christopher
C
Preston
D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000235:genetics* / Q000378:metabolism; D001315:Australia; D005784:Gene Amplification; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D053209:Herbicide Resistance / Q000235:genetics*; D006540:Herbicides / Q000494:pharmacology*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D006109:Poaceae / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D000097797:Glyphosate
D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D005998:Glycine; D006540:Herbicides; D010940:Plant Proteins; D000097797:Glyphosate
Chloris truncata; EPSPS copy number; EPSPS gene amplification; dose response; glyphosate resistance; shikimate assay; target-site mutation