Anhui Province Key Laboratory of Crop Integrated Pest Management, School of Plant Protection, Anhui Agricultural University, Hefei, China.
Anhui Province Engineering Laboratory for Green Pesticide Development and Application, School of Plant Protection, Anhui Agricultural University, Hefei, China.
Pest Manag Sci. 2022 Mar;78(3):1176-1186. doi: 10.1002/ps.6734. Epub 2021 Dec 13.
Chinese sprangletop (Leptochloa chinensis (L.) Nees) is an invasive grass weed severely infesting rice fields across China. In October 2020, a suspected resistant Leptochloa chinensis population HFFD3 that survived the acetyl-CoA carboxylase (ACCase)-inhibiting herbicide cyhalofop-butyl applied at its field-recommended rate was collected from a rice field in Feidong County, Anhui Province, China. This study aimed to determine the resistance profile of HFFD3 to ACCase inhibitors and to investigate its mechanisms of resistance to cyhalofop-butyl.
Single-dose testing confirmed that HFFD3 had evolved resistance to cyhalofop-butyl. Two loci encoding plastidic ACCase were each amplified from the susceptible (S) and resistant (R, HFFD3) individual plants. Target gene sequencing and derived cleaved amplified polymorphic sequence assay revealed all the R plants carried a Trp-2027-Leu substitution in their ACCase1,2 copies. Dose-response bioassays revealed that HFFD3 was highly resistant to cyhalofop-butyl and exhibited cross-resistance to metamifop, fenoxaprop-P-ethyl, quizalofop-P-ethyl, and clethodim. Pre-treatment with piperonyl butoxide and 4-chloro-7-nitrobenzoxadiazole considerably reversed the resistance of the R plants to cyhalofop-butyl, by 23% and 43%, respectively. Liquid chromatography-tandem mass spectrometry analysis suggested the metabolic rates of cyhalofop-butyl were significantly faster in the R than in the S plants.
This study confirmed the first case of an arable weed species featuring cross-resistance to ACCase-inhibiting herbicides due to a novel Trp-2027-Leu mutation of ACCase. Target gene mutation and cytochrome P450s- and glutathione-S-transferases-involved enhanced metabolism may have simultaneously participated in the resistance of HFFD3 population to cyhalofop-butyl.
中国看麦娘（Leptochloa chinensis (L.) Nees）是一种严重入侵中国稻田的杂草。2020 年 10 月，在中国安徽省肥东县的一个稻田中，从一个经乙酰辅酶 A 羧化酶（ACCase）抑制剂草铵膦丁酯田间推荐剂量处理后仍存活的疑似抗性看麦娘种群 HFFD3 中采集到该样本。本研究旨在确定 HFFD3 对 ACCase 抑制剂的抗性特征，并研究其对草铵膦丁酯的抗性机制。
单剂量测试证实 HFFD3 对草铵膦丁酯产生了抗性。从小麦草敏感（S）和抗性（R，HFFD3）个体植株中分别扩增出编码质体 ACCase 的两个基因座。靶基因测序和衍生的切割扩增多态性序列分析显示，所有 R 植株的 ACCase1 和 2 拷贝均携带一个色氨酸 2027 亮氨酸取代。剂量反应生物测定显示，HFFD3 对草铵膦丁酯具有高度抗性，并表现出对精恶唑禾草灵、精吡氟禾草灵、高效氟吡甲禾灵和稀禾定的交叉抗性。用增效醚和 4-氯-7-硝基苯并恶二唑预处理可分别使 R 植株对草铵膦丁酯的抗性逆转 23%和 43%。液相色谱-串联质谱分析表明，R 植株对草铵膦丁酯的代谢速度明显快于 S 植株。
本研究证实了首例农田杂草因 ACCase 的新型色氨酸 2027 亮氨酸突变而对 ACCase 抑制剂产生的交叉抗性。靶基因突变和细胞色素 P450 酶和谷胱甘肽 S-转移酶参与的增强代谢可能同时参与了 HFFD3 种群对草铵膦丁酯的抗性。
