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Confirmation and mechanism of glyphosate resistance in tall windmill grass ( Chloris elata ) from Brazil
Author(s) -
Brunharo Caio ACG,
Patterson Eric L,
Carrijo Daniela R,
de Melo Marcel SC,
Nicolai Marcelo,
Gaines Todd A,
Nissen Scott J,
Christoffoleti Pedro J
Publication year - 2016
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.4205
Subject(s) - glyphosate , biology , weed , botany , poa annua , population , dry weight , dry matter , horticulture , agronomy , sociology , demography
BACKGROUND Overreliance on glyphosate as a single tool for weed management in agricultural systems in Brazil has selected glyphosate‐resistant populations of tall windmill grass ( Chloris elata Desv.). RESULTS Two C. elata populations, one glyphosate resistant ( GR ) and one glyphosate susceptible ( GS ), were studied in detail for a dose–response experiment and for resistance mechanism. The dose causing 50% reduction in dry weight was 620 g a.e. ha −1 for GR and 114 g ha −1 for GS , resulting in an R/S ratio of 5.4. GS had significantly higher maximum 14 C ‐glyphosate absorption into the treated leaf (51.3%) than GR (39.5%), a difference of 11.8% in maximum absorption. GR also retained more 14 C ‐glyphosate in the treated leaf (74%) than GS (51%), and GR translocated less glyphosate (27%) to other plant parts (stems, roots and root exudation) than GS (36%). There were no mutations at the Pro106 codon in the gene encoding 5‐enolpyruvylshikimate‐3‐phosphate synthase ( EPSPS ). There was no difference in EPSPS genomic copy number or EPSPS transcription between GS and GR populations. CONCLUSION Based on these data, reduced glyphosate absorption and increased glyphosate retention in the treated leaf contribute to glyphosate resistance in this C. elata population from Brazil. © 2015 Society of Chemical Industry