Cotton (Gossypium hirsutum L.) cultivars resistant to different herbicides have generated important advances in crop management. There is a wide range of cotton resistance to herbicides, however, commercial imidazolinone (IMI)-tolerant cultivars are not available. In this research, a new mutation that confers tolerance to IMI in cotton was isolated in the M₂ generation after seed mutagenic treatments with sodium azide water solutions. The mode of inheritance of the trait was evaluated in the F₂ generation by the application of imazethapyr. The inheritance corresponds to a semidominant type with a 1:2:1 distribution of tolerant/intermediate tolerance/not tolerant, in agreement with that observed in most IMI-tolerant crops. The IMI-tolerant line behavior was evaluated in the field nursery after the application of the herbicide in the form of foliar and pre-emergence sprays. The tolerance level was high in pre-emergence applications and intermediate in foliar applications compared with the nontolerant genotype, which showed a decrease in fiber yield and quality with both methods of application. After sequencing the acetohydroxyacid synthase (AHAS) gene, a point mutation corresponding to Ala205Val in the AHAS enzyme was found, which suggests it could be responsible for the increased IMI tolerance observed in cotton line SP 4172-32. Based on results from field assays, it can be concluded that this mutant is a promising experimental line that can be used in obtaining IMI- tolerant commercial cotton cultivars.

中文翻译：

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棉花耐咪唑啉酮新突变体的分离与鉴定

对不同除草剂具有抗性的棉花 ( Gossypium hirsutum L.) 品种在作物管理方面取得了重要进展。棉花对除草剂有广泛的抗性，但是，商业上没有耐咪唑啉酮 (IMI) 的品种。在这项研究中，在用叠氮化钠水溶液进行种子诱变处理后，在 M ₂代中分离出一种赋予棉花 IMI 耐受性的新突变。_{在 F 2}中评估性状的遗传模式应用咪草烟生成。该遗传对应于具有 1:2:1 耐受/中等耐受/不耐受分布的半显性类型，与大多数 IMI 耐受作物中观察到的一致。在以叶面和出苗前喷雾形式施用除草剂后，在田间苗圃中评估了 IMI 耐受性品系行为。与非耐受基因型相比，出苗前应用的耐受水平较高，叶面应用的耐受水平居中，这表明两种应用方法的纤维产量和质量均有所下降。在对乙酰羟酸合酶 (AHAS) 基因进行测序后，发现了 AHAS 酶中对应于 Ala205Val 的点突变，这表明它可能是棉花品系 SP 4172-32 中观察到的 IMI 耐受性增加的原因。