ABSTRACT Acetyl-coenzyme A carboxylase (ACCase) inhibitors such as haloxyfop, pinoxaden and clethodim selectively control grass weed species in many types of crop. Here, we characterised two populations of Lolium multiflorum (Italian ryegrass), R and RV, from South Canterbury and Central Otago respectively, that were suspected to be resistant to ACCase-inhibiting herbicides. Based on 50% reduction in biomass (GR50), in two dose–response experiments, both populations were highly resistant to haloxyfop with resistance factors (RF) >400 times, but resistance to pinoxaden was low (RF of 2). Furthermore, population R was found to be moderately resistant to clethodim (RF >4, based on 50% reduction in survival (LD50)), but population RV had RFs barely greater than 1, based on GR50. Gene sequencing showed that the same target site mutation (Ile-2041-Asn) was associated with resistance to the three herbicides in both populations. The zygosity of the resistance alleles in the plants tested could cause the differences in resistance to clethodim observed between the populations, even though they carried the same mutation. This is the first report of the mechanism of resistance to ACCase-inhibiting herbicides in Italian ryegrass from New Zealand.

中文翻译：

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目标位点突变 Ile-2041-Asn 与黑麦草对 ACCase 抑制性除草剂的抗性有关

摘要 乙酰辅酶 A 羧化酶 (ACCase) 抑制剂，例如氟啶虫胺、吡咯酯和烯草醚，可选择性地控制多种作物中的禾本科杂草。在这里，我们表征了分别来自南坎特伯雷和中奥塔哥的两种黑麦草（意大利黑麦草）种群 R 和 RV，它们被怀疑对 ACCase 抑制性除草剂具有抗性。基于生物量 (GR50) 减少 50%，在两个剂量反应实验中，两个种群对氟啶虫胺具有高度抗性，抗性因子 (RF) > 400 倍，但对唑草胺的抗性较低（RF 为 2）。此外，发现群体 R 对烯草酮具有中度抗性（RF > 4，基于存活率降低 50% (LD50)），但群体 RV 的 RF 几乎不大于 1，基于 GR50。基因测序表明，相同的靶位点突变 (Ile-2041-Asn) 与两个种群对三种除草剂的抗性有关。受试植物中抗性等位基因的合子性可能导致种群之间观察到的对烯草酮抗性的差异，即使它们携带相同的突变。这是新西兰意大利黑麦草对ACCase抑制性除草剂抗性机制的首次报道。