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1 July 2017 Target-Site Resistance to Fenoxaprop-P-ethyl in Keng Stiffgrass (Sclerochloa kengiana) from China
Haitao Gao, Jiaxing Yu, Lang Pan, Xibao Wu, Liyao Dong
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Keng stiffgrass is a serious farmland grass weed distributed globally in winter wheat fields and rice—wheat double-cropping areas. The intensive use of acetyl-CoA carboxylase (ACCase)-inhibiting herbicides has led to the evolution of resistance in a growing number of grass weeds. In this study, whole-plant pot bioassay experiments were conducted to establish that a Keng stiffgrass population from eastern China, JYJD-2, has evolved high-level resistance to fenoxaprop-P-ethyl and moderate resistance to quizalofop-P-ethyl and pinoxaden. Using the derived cleaved amplified polymorphic sequence method, a tryptophan-to-cysteine mutation at codon position 1999 (W1999C) was detected in the ACCase gene of the resistant population JYJD-2. Of the 100 JYJD-2 plants tested, we found 47 heterozygous resistant and 53 homozygous sensitive individuals. In vitro ACCase assays revealed that the IC50 value of the ACCase activity of the resistant population JYJD-2 was 6.48-fold higher than that of the susceptible population JYJD-1. To the best of our knowledge, this is the first report of the occurrence of W1999C mutation in the ACCase gene of fenoxaprop-P-ethyl—resistant Keng stiffgrass. This study confirmed the resistance of Keng stiffgrass to the ACCase inhibitor fenoxaprop-P-ethyl, cross-resistance to other ACCase inhibitors, and the resistance being conferred by specific ACCase point mutations at amino acid position 1999.

Nomenclature: fenoxaprop-P-ethyl; quizalofop-P-ethyl; pinoxaden; Keng stiffgrass, Sclerochloa kengiana (Ohwi) Tzvel.; rice, Oryza sativa L.; wheat, Triticum aestivum L.

© Weed Science Society of America, 2017
Haitao Gao, Jiaxing Yu, Lang Pan, Xibao Wu, and Liyao Dong "Target-Site Resistance to Fenoxaprop-P-ethyl in Keng Stiffgrass (Sclerochloa kengiana) from China," Weed Science 65(4), 452-460, (1 July 2017).
Received: 26 September 2016; Accepted: 1 March 2017; Published: 1 July 2017

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