In wheat (Triticum aestivum L.), cultivars resistant to imidazolinone herbicides are an important tool for weed management. The target site of imidazolinones is acetohydroxyacid synthase (AHAS), an enzyme coded by three homeologous genes (ahasL‐A1, ahasL‐B1, and ahasL‐D1). This study aimed to evaluate the effect of the imidazolinone herbicide imazamox on a single‐gene (AhasL‐D1) resistant line (R1) and a two‐gene (AhasL‐B1 and AhasL‐D1) resistant line (R2) at multiple biological levels. These lines showed variation in the transcriptional levels of ahasL homeologs, but no differences in total AHAS activity. The relative contribution of resistant alleles to the ahasL transcript pool accounted for 47% in the R1 line and 77% in the R2 line. The in vitro AHAS inhibition of the R1 line was intermediate between the R2 and the susceptible lines. At an anatomical level, high imazamox concentrations induced alterations in the root tip features of R1 plants but did not affect R2 plants, whereas at in vivo AHAS activity and whole‐plant levels, both resistant lines showed high resistance. The herbicide dose that reduced shoot biomass of resistant lines by 50% was 35‐fold higher than that of the susceptible line. We conclude that homeolog variation allows a higher contribution of resistance genes to the ahasL transcript pool in the R1 and R2 lines. Although both resistant lines showed high whole‐plant resistance, the differential root damage induced by imazamox between wheat lines suggests that two‐gene resistant cultivars could be an effective option to avoid the negative impacts caused by herbicide residues in the soil.

中文翻译：

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鉴定一基因和二基因抗Imoxamox小麦品系的综合方法

在小麦（Triticum aestivum L.）中，对咪唑啉酮类除草剂具有抗性的品种是控制杂草的重要工具。咪唑啉酮的靶位是乙酰羟酸合酶（AHAS），一种由三个同源基因（ahasL-A1，ahasL-B1和ahasL-D1）编码的酶。这项研究旨在评估咪唑啉酮除草剂咪唑胺在多个生物学水平上对单基因（AhasL-D1）抗性品系（R1）和两个基因（AhasL-B1和AhasL-D1）抗性品系（R2）的影响。这些系显示了ahasL转录水平的变化同源物，但总AHAS活性无差异。耐药等位基因对ahasL转录本库的相对贡献在R1系中占47％，在R2系中占77％。R1系的体外AHAS抑制作用介于R2和易感系之间。在解剖学水平上，高的Imazamox浓度诱导R1植物的根尖特征发生变化，但不影响R2植物，而在体内AHAS活性和全植物水平下，两个抗性品系均显示出高抗性。使抗性品系的茎生物量减少50％的除草剂剂量比易感品系高35倍。我们得出结论，同源同源变异允许抗性基因对ahasL的贡献更大R1和R2行中的转录本池。尽管两个抗性品系均表现出较高的全株抗性，但小麦品系之间的地衣草诱导的不同根系损害表明，两个基因的抗性品种可能是避免土壤中除草剂残留物造成负面影响的有效选择。