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First report of resistance to acetolactate‐synthase‐inhibiting herbicides in yellow nutsedge ( Cyperus esculentus ): confirmation and characterization
Author(s) -
Tehranchian Parsa,
Norsworthy Jason K,
Nandula Vijay,
McElroy Scott,
Chen Shu,
Scott Robert C
Publication year - 2015
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.3922
Subject(s) - acetolactate synthase , sulfonylurea , biology , bioassay , cross resistance , cyperus , gene , horticulture , botany , genetics , microbiology and biotechnology , insulin
BACKGROUND Yellow nutsedge is one of the most problematic sedges in Arkansas rice, requiring the frequent use of halosulfuron (sulfonylurea) for its control. In the summer of 2012, halosulfuron at 53 g ha −1 (labeled field rate) failed to control yellow nutsedge. The level of resistance to halosulfuron was determined in the putative resistant biotype, and its cross‐resistance to other acetolactate synthase ( ALS ) inhibitors from four different herbicide families. ALS enzyme assays and analysis of the ALS gene were used to ascertain the resistance mechanism. RESULTS None of the resistant plants was killed by halosulfuron at a dose of 13 568 g ha −1 (256× the field dose), indicating a high level of resistance. Based on the whole‐plant bioassay, the resistant biotype was not controlled by any of the ALS ‐inhibiting herbicides (imazamox, imazethapyr, penoxsulam, bispyribac, pyrithiobac‐sodium, bensulfuron and halosulfuron) tested at the labeled field rate. The ALS enzyme from the resistant biotype was 2540 times less responsive to halosulfuron than the susceptible biotype, and a Trp 574 ‐to‐Leu substitution was detected by ALS gene sequencing using the Illumina HiSeq . CONCLUSION The results suggest a target‐site alteration as the mechanism of resistance in yellow nutsedge, which accounts for the cross‐resistance to other ALS ‐inhibiting herbicide families. © 2014 Society of Chemical Industry