Euphorbia heterophylla populations endued with resistance to both imazethapyr (an acetolactate synthase inhibitor) and fomesafen (a protoporphyrinogen oxidase inhibitor) were first detected in Brazil in 2004. The objectives of this study were to determine the number and dominance of genes conferring imazethapyr and fomesafen resistance in E. heterophylla and to establish the types of inheritance of the resistance traits. It was hypothesised that two dominant nuclear genes control this herbicide resistance and each gene confers resistance to a single herbicide. We crossed a susceptible (S) and a multiple‐resistant (R) E. heterophylla biotype and generated F₁ families which, in turn, were self‐fertilised to produce F₂ families. Backcrosses of the F₁ families with the S‐ and R parental biotypes resulted in BCₛ and BCᵣ families respectively. The F₁, F₂, BCₛ and BCᵣ families and the S and R parental biotypes were subjected to imazethapyr and fomesafen wherein each herbicide was used as a selecting agent. F₁ plants and the S‐ and R parental biotypes were used to evaluate the dominance of the resistance trait in multiple‐dose bioassays with imazethapyr and fomesafen. The observed frequencies of resistant plants in the F₁, F₂, BCₛ and BCᵣ families did not significantly differ from the expected frequencies for a resistance trait regulated by two dominant genes in which each gene confers resistance to a single herbicide. The lack of difference in herbicide response between the F₁ family and the R parental biotype was taken as evidence for completely dominant resistance to imazethapyr and fomesafen. Herbicide resistance in E. heterophylla presents with dominant monogenic nuclear inheritance for each herbicide mode of action. Our findings underscore the necessity and urgency of adopting integrated strategies to control E. heterophylla and to inhibit the evolution of new herbicide‐resistant strains.

中文翻译：

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多重抗除草剂异叶大戟种群中氟磺胺草醚和咪草烟抗性的遗传

2004 年在巴西首次发现了对咪草烟（一种乙酰乳酸合酶抑制剂）和氟磺胺草醚（一种原卟啉原氧化酶抑制剂）具有抗性的异叶大戟种群。本研究的目的是确定赋予咪草烟和氟磺胺草醚抗性的基因的数量和优势在 E.heterophylla 中并确定抗性性状的遗传类型。假设两个显性核基因控制这种除草剂抗性，并且每个基因赋予对单一除草剂的抗性。我们杂交了易感 (S) 和多重抗性 (R) E.heterophylla 生物型并产生了 F₁ 家族，而这些家族又通过自体受精产生了 F2 家族。F₁ 家族与 S- 和 R 亲本生物型的回交分别导致 BCₛ 和 BCᵣ 家族。F₁，F₂、BCₛ 和 BCᵣ 家族以及 S 和 R 亲本生物型经过咪草烟和氟磺胺草醚处理，其中每种除草剂都用作选择剂。F₁ 植物和 S- 和 R 亲本生物型用于评估在咪唑乙烟酸和氟磺胺草醚的多剂量生物测定中抗性性状的优势。F₁、F₂、BCₛ 和 BCᵣ 家族中抗性植物的观察频率与由两个显性基因调控的抗性性状的预期频率没有显着差异，其中每个基因赋予对单一除草剂的抗性。F₁ 家族和 R 亲本生物型之间在除草剂反应方面没有差异被认为是对咪草烟和氟磺胺草醚完全显性抗性的证据。E. 除草剂抗性 对于每种除草剂作用方式，heterophylla 呈现显性单基因核遗传。我们的研究结果强调了采取综合策略来控制太子草和抑制新的抗除草剂菌株进化的必要性和紧迫性。