A redroot pigweed (Amaranthus retroflexus L.) population (HN-02) collected from Nenjiang County, Heilongjiang Province, exhibited multiple resistance to fomesafen and nicosulfuron. The purposes of this study were to characterize the herbicide resistance status of an HN-02 population for both acetolactate synthase (ALS) and protoporphyrinogen oxidase (PPO) inhibitors and the response to other herbicides and to investigate the target site-based mechanism governing fomesafen and nicosulfuron resistance. Three mutations, Ala-205-Val and Trp-574-Leu mutations in the ALS gene and an Arg-128-Gly mutation in the PPX2 gene, were identified in individual resistant plants. An HN-02F1-1 subpopulation homozygous for the Ala-205-Val and Arg-128-Gly mutations was generated, and whole-plant experiments confirmed multiple resistance to PPO inhibitors (fomesafen, fluoroglycofen-ethyl, and acifluorfen) and ALS inhibitors (imidazolinones [IMI], sulfonylureas [SU], and triazolopyrimidines [TP]) in the HN-02F1-1 plants, which presented resistance index values ranging from 8.3 to 110; however, these plants were sensitive to flumioxazin, fluroxypyr-meptyl, and 2,4-D butylate. In vitro ALS enzyme activity assays revealed that, compared with ALS from susceptible plants, ALS from the HN-02F1-1 plants was 15-, 28- and 320-fold resistant to flumetsulam, nicosulfuron, and imazethapyr, respectively. This study confirms the first case of multiple resistance to PPO and ALS inhibitors in A. retroflexus and determines that the target-site resistance mechanism was produced by Ala-205-Val and Arg-128-Gly mutations in the ALS gene and PPX2 gene, respectively. In particular, the Ala-205-Val mutation was found to endow resistance to three classes of ALS inhibitors: TP, SU, and IMI.

中文翻译：

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红根藜 (Amaranthus retroflexus) 对 PPO 和 ALS 抑制剂的多重耐药性

红根藜 (苋菜从黑龙江省嫩江县采集的 L.) 种群 (HN-02) 对氟磺胺草醚和烟嘧磺隆具有多重耐药性。本研究的目的是描述 HN-02 种群对乙酰乳酸合酶 (ALS) 和原卟啉原氧化酶 (PPO) 抑制剂的抗性状态以及对其他除草剂的反应，并研究基于靶点的控制氟磺草胺和烟嘧磺隆耐药。三个突变，Ala-205-Val 和 Trp-574-Leu 突变肌萎缩侧索硬化症基因和 Arg-128-Gly 突变PPX2基因，在个别抗性植物中被鉴定。产生了一个 Ala-205-Val 和 Arg-128-Gly 突变纯合子 HN-02F1-1 亚群，整株植物实验证实了对 PPO 抑制剂（氟磺胺草醚、氟乙醚和三氟草醚）和 ALS 抑制剂的多重耐药性。 HN-02F1-1 植物中的咪唑啉酮类 [IMI]、磺酰脲类 [SU] 和三唑并嘧啶类 [TP])，其抗性指数值范围为 8.3 至 110；然而，这些植物对氟嘧啶、氟草烟和 2,4-D 丁酯敏感。体外 ALS 酶活性测定表明，与来自易感植物的 ALS 相比，来自 HN-02F1-1 植物的 ALS 对氟美舒仑、烟嘧磺隆和咪草烟的抗性分别是 15 倍、28 倍和 320 倍。A. 反曲并确定靶位点抗性机制是由 Ala-205-Val 和 Arg-128-Gly 突变产生的肌萎缩侧索硬化症基因和PPX2基因，分别。特别是，发现 Ala-205-Val 突变赋予对三类 ALS 抑制剂的抗性：TP、SU 和 IMI。