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ARS Home » Pacific West Area » Pullman, Washington » WHGQ » Research » Publications at this Location » Publication #415749
Research Project: Ecology and Genomics of Soilborne Pathogens, Beneficial Microbes, and the Microbiome of Wheat, Barley, and Biofuel Brassicas

Location: Wheat Health, Genetics, and Quality Research

Title: Metabolism of halauxifen acid is regulated by genes located on wheat chromosome 5A

Author
item Landau, Olivia
item CONCEPCION, JEANAFLOR - University Of Illinois
item RIECHERS, DEAN - University Of Illinois

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2024
Publication Date: 4/15/2024
Citation: Landau, O.A., Concepcion, J.C., Riechers, D.E. 2024. Metabolism of halauxifen acid is regulated by genes located on wheat chromosome 5A. Weed Science. https://doi.org/10.1017/wsc.2024.24.
DOI: https://doi.org/10.1017/wsc.2024.24

Interpretive Summary: The detoxification of halauxifen-methyl was compared between different wheat alien substitution and nullisomic-tetrasomic lines. Lines lacking chromosome 5A consistently accumulated more halauxifen acid compared to lines that maintained 5A over time, indicating that genes encoding halauxifen acid-detoxifying enzymes are located on chromosome 5. These findings provide evidence for the location of genes relevant to halauxifen acid detoxification, and this knowledge can be utilized in future genomic and/or transcriptomic research to identify candidate genes. These genes could be utilized to generate halauxifen-methyl-resistant transgenic cultivars in species that are normally sensitive to this herbicide, such as soybean, cotton, and other dicots. Improved knowledge of such genes and their encoded enzymes can be incorporated into research regarding halauxifen acid detoxification in related crop and weed species.

Technical Abstract: Allohexaploid wheat (Triticum aestivum L.) is tolerant to halauxifen-methyl (HM) via rapid detoxification of the phytotoxic form of HM, halauxifen acid (HA), to non-phytotoxic metabolites. Previous research utilizing ‘Chinese Spring’ (CS) wheat, alien substitution (i.e., endogenous chromosome pair substituted with a homoeologous pair from diploid Sears’ goatgrass (Aegilops searsii M. Feldman & M. Kislev) (AS), or nullisomic-tetrasomic (NT) lines indicated plants lacking chromosome 5A are more sensitive than CS to HM. We hypothesized the increased HM sensitivity of these plants results from losing gene(s) on chromosome 5A associated with HA metabolism, which leads to a reduced HA detoxification rate relative to CS. To compare HA abundance among AS, CS, alien substitution, and NT lines during a time course, two excised-leaf studies using unlabeled HM and liquid chromatography–mass spectrometry analyses were performed. Aegilops searsii accumulated more HA than CS did, and each substitution line at 8, 12, and 24 h after treatment (HAT). Furthermore, only the wheat substitution line lacking chromosome 5A displayed greater abundance of HA relative to CS (2.4- to 3.8-fold, depending on the time point). In contrast, HA abundances in lines possessing chromosome 5A were not different than HA abundances in CS at all time points. When NT lines were compared with CS, the nullisomic 5D-tetrasomic 5A (N5D-T5A) line displayed similar HA abundance, whereas the nullisomic 5A-tetrasomic 5D (N5A-T5D) accumulated approximately 3-fold more HA at 12 and 24 HAT. These results biochemically support the hypothesis that genes encoding HA-detoxifying enzyme(s) are located on wheat chromosome 5A and corroborate findings from previous greenhouse phenotypic experiments. Future experimentation is needed to identify and characterize genes and enzymes on wheat chromosome 5A involved with HA detoxification, which may include cytochrome P450 monooxygenases, unknown oxidases, UDP-dependent glucosyltransferases, or, potentially, transcription factors that regulate expression of these genes associated with HA detoxification.