Natural tolerance in hexaploid bread wheat (Triticum aestivum L.) to synthetic auxin herbicides is primarily due to rapid metabolic detoxification, but genes encoding these herbicide-detoxifying enzymes have yet to be identified. Herbicide safeners are commonly applied in wheat to achieve herbicide tolerance by inducing the expression and activity of herbicide-detoxifying enzymes. While safeners have been utilized for decades, knowledge of mechanisms that induce gene expression is limited. Our objective was to identify wheat chromosomes possessing genes that endow natural or safener-induced tolerance to halauxifen-methyl (HM), a postemergence (POST) wheat-selective synthetic auxin herbicide, using alien substitution (the S genome of Aegilops searsii) and aneuploid lines. Two POST rates of HM were applied to seedlings with 1-2 leaves (Zadoks stages 11-12), and the highest HM rate was also applied with the safener cloquintocet-mexyl (CM). Wheat chromosomes possessing genes associated only with natural HM tolerance were identified because Ae. searsii is HM-sensitive but CM-responsive. Lines with substitutions for 5A and 5B displayed sensitivity to HM, and experiments with nullisomic-tetrasomic (NT) lines further indicated major genes associated with HM tolerance are present on 5A and 5B chromosomes. However, the genes on 5A appear to play a larger role because lines lacking 5A chromosomes displayed more sensitivity than lines lacking 5B. Overall, these results can be utilized to guide future transcriptome analyses to identify candidate genes that confer HM tolerance in wheat.

六倍体面包小麦（Triticum aestivum L.）对合成植物生长素除草剂的天然耐受性主要是由于快速的代谢解毒作用，但是尚未确定编码这些除草剂解毒酶的基因。除草剂安全剂通常用于小麦中，通过诱导除草剂解毒酶的表达和活性来达到除草剂耐受性。尽管安全剂已经使用了数十年，但是诱导基因表达的机制的知识仍然有限。我们的目标是使用外来替代来鉴定具有赋予天然或安全诱导的耐受性的小麦染色体的基因，该基因使用异源替代（后代Aegilops searsii的小麦选择性合成生长素除草剂））和非整倍体系。对1-2片叶子的幼苗（Zadoks第11至12阶段）施以HM的两种POST率，同时使用安全的氯喹噻吩甲醚（CM）也施以最高的HM率。由于Ae，鉴定出具有仅与天然HM耐受性相关的基因的小麦染色体。西尔西对HM敏感，但对CM敏感。用5A和5B替代的品系显示出对HM的敏感性，并且用无效等位四体（NT）品系进行的实验进一步表明与HM耐受性相关的主要基因存在于5A和5B染色体上。然而，5A上的基因似乎起着更大的作用，因为缺少5A染色体的品系比缺少5B的品系显示出更高的敏感性。总体而言，这些结果可用于指导未来的转录组分析，以鉴定赋予小麦HM耐性的候选基因。