Cross-resistance pattern to ACCase-inhibiting herbicides in a rare Trp-2027-Ser mutation Chinese sprangletop (Leptochloa chinensis) population

Guohui Yuan1, Zhihui Tian1, Tao Li1, Zhenguan Qian1, Wenlei Guo2, and Guohui Shen1*
Chinese sprangletop (Leptochloa chinensis [L.] Nees) is an invasive and troublesome grass weed in the aerobic rice fields in China. The extensive and repeated use of acetyl-CoA carboxylase (ACCase)-inhibiting herbicides has resulted in herbicide resistance in this weed. The objectives of this study were to determine the resistance levels to ACCase-inhibiting herbicides of the putative resistant Chinese sprangletop population CM9-1, collected from a paddy field in Shanghai city, in comparison to the susceptible population SJ3-1, and to characterize its molecular resistance mechanism. The whole- plant dose-response experiments suggested that the population CM9-1 had high-level resistance to cyhalofop-butyl, metamifopandfenoxaprop-P-ethyl, with resistance index of 27.8, 21.4 and 26.2, respectively, andlow-level resistance to sethoxydim and pinoxaden, with resistance index of 2.1 and 2.9, respectively, but was sensitive to clethodim. Sequence analysis of the CT domain of ACCase gene revealed aTrp-2027-Ser mutation in resistant plants of the CM9-1 population. This is the first report of the cross-resistance pattern of the Trp-2027-Ser mutation to ACCase-inhibiting herbicides in Chinesesprangletop.
Keywords: ACCase-inhibiting herbicide, cross-resistance, target-site resistance mutation.
1Eco-environmental Protection Research Institute, Shanghai Engineering Research Centre of Low-Carbon Agriculture, Shanghai Academy of Agricultural Sciences, 201403 Shanghai, China.
*Corresponding author (ghshen65@163.com).
2Institute of Plant Protection, Guangdong Academy of Agricultural Sciences, 510640 Guangzhou, China.