Organophosphate insecticides, which have the capacity to inhibit specific herbicide-degrading (cytochrome P450) enzymes, have been used to explore metabolic herbicide-resistance mechanisms in weeds. This study investigates the response of seven field-selected rigid ryegrass (Lolium rigidum Gaudin) populations to herbicides from three different sites of action in the presence or absence of the P450 inhibitor phorate. Phorate antagonized the thiocarbamate herbicides triallate and prosulfocarb (8-fold increase in LD50) in multiple resistant L. rigidum populations with resistance to three different site-of-action herbicides. In contrast, phorate synergized trifluralin and propyzamide in some populations, reducing the LD50 by 50%. Conversely, treatment with phorate had no significant effect on the LD50 for S-metolachlor or pyroxasulfone (inhibitors of very-long-chain fatty-acid synthesis). Phorate has diverse effects that are herbicide and population dependant in field-selected L. rigidum, suggesting P450 involvement in the metabolism of trifluralin and failure to activate thiocarbamate herbicides in these populations. This research highlights the need for implementation of diverse approaches other than herbicide alone as part of a long-term integrated strategy to reduce the likelihood of metabolism-based resistance to PPI herbicides in L. rigidum.

中文翻译：

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田间选择的抗除草剂硬性黑麦草 (Lolium rigidum) 种群对甲拌磷与 PPI 除草剂组合的不同反应

有机磷杀虫剂具有抑制特定除草剂降解（细胞色素 P450）酶的能力，已被用于探索杂草的代谢除草剂抗性机制。本研究调查了七种田间选择的硬质黑麦草（黑麦草在存在或不存在 P450 抑制剂甲拌磷的情况下，Gaudin) 从三个不同的作用位点对除草剂产生影响。甲拌磷能拮抗硫代氨基甲酸盐除草剂三甲酸盐和磺草威（LD 增加 8 倍）50) 在多重抗刚体乳杆菌对三种不同作用位点除草剂具有抗性的种群。相比之下，甲拌磷在某些人群中协同氟乐灵和丙脲，降低了 LD5050%。相反，甲拌磷处理对 LD 没有显着影响50为了小号-异丙甲草胺或pyroxasulfone（超长链脂肪酸合成抑制剂）。甲拌磷具有多种作用，在选择的田间除草剂和种群依赖刚体乳杆菌，表明 P450 参与氟乐灵的代谢，并且未能在这些人群中激活硫代氨基甲酸酯类除草剂。这项研究强调需要实施除单独除草剂以外的多种方法，作为长期综合战略的一部分，以降低基于代谢的 PPI 除草剂抗性的可能性刚体乳杆菌.