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ARS Home » Pacific West Area » Pullman, Washington » WHGQ » Research » Publications at this Location » Publication #419072
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: Transcriptomic analysis reveals cloquintocet-mexyl-inducible genes in hexaploid wheat (Triticum aestivum L.)

Author
item Landau, Olivia
item JAMISON, BRENDAN - University Of Illinois
item RIECHERS, DEAN - University Of Illinois

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2025
Publication Date: 2/18/2025
Citation: Landau, O.A., Jamison, B.V., Riechers, D.E. 2025. Transcriptomic analysis reveals cloquintocet-mexyl-inducible genes in hexaploid wheat (Triticum aestivum L.). PLOS ONE. 20(2). Article 0319151. https://doi.org/10.1371/journal.pone.0319151.
DOI: https://doi.org/10.1371/journal.pone.0319151

Interpretive Summary: Leaf tissue from untreated and cloquintocet-mexyl(CM)-treated wheat (Triticum aestivum L.) was utilized for RNA-Seq analysis and identified numerous genes significantly induced by CM. Several of these genes encode enzymes associated with herbicide/xenobiotic metabolism, such as a CYP81A gene located on chromosome 5A (denoted as CYP81A-5A). The CYP81A sub-family of of cytochrome P450s (CYPs) have been frequently implicated in the detoxification of multiple different classes of herbicides, including synthetic auxins. Further investigation with CYP81A-5A was conducted with RT-qPCR, which validated that its expression is induced by CM. These findings provide evidence of specific CM-inducible genes in wheat that are necessary for herbicide detoxification, such as halauxifen-methyl (HM), a synthetic auxin that is commonly utilized with CM. 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 HM detoxification in related crop and weed species.

Technical Abstract: Identification and characterization of genes encoding herbicide-detoxifying enzymes is lacking in allohexaploid wheat (Triticum aestivum L.). Detoxification gene expression is frequently induced by herbicide safeners and implies the encoded enzymes serve a role in herbicide metabolism. Cloquintocet-mexyl (CM) is a safener commonly utilized with halauxifen-methyl (HM), a synthetic auxin herbicide whose phytotoxic form is halauxifen acid (HA). The first objective was to identify candidate HA-detoxifying genes via RNA-Seq by comparing untreated and CM-treated leaf tissue. A member of the CYP81A subfamily of cytochrome P450s (CYPs) was identified (denoted as CYP81A-5A), which are capable of catalyzing synthetic auxin detoxification. To investigate CYP expression induced by HM and CM, the second objective was to measure gene-specific expression of CYP81A-5A and its homoeologs (CYP81A-5B and CYP81A-5D) in untreated leaf tissue and leaf tissue treated with CM and HM over time using RT-qPCR. Relative to the reference gene (ß-tubulin), basal CYP expression is high, expression among these CYPs varies over time, and expression for all CYPs is CM-inducible. Further analysis of CYP81A-5A, such as gene knock-out, overexpression experiments, or in vitro activity assays with purified enzyme are necessary to test the hypotheses that the encoded CYP detoxifies HA and that CM upregulates this reaction.