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bioRxiv · 10.1101/2023.06.05.543806

Loss of OsARF18 confers glufosinate ammonium herbicide resistance in rice

Xia, J.-Q.·He, D.-Y.·Zhao, P.-X.·Xiang, C.
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Abstract

Weed is one of the major biotic stresses that causes severe loss of crop yield. Herbicide is one of the most cost-effective ways to control weeds. Thus, the development of herbicide-resistant crops is critical for the application of herbicides. To isolate new glufosinate ammonium resistance loci, we screened a rice ethyl methyl sulfonate-mutagenized library and obtained the glufosinate ammonium-resistant mutant gar1-1. GAR1 encodes auxin response factor 18 (OsARF18). A G-to-A substitution in the coding region of OsARF18 results in loss of function of OsARF18 and thereby enhances glufosinate ammonium resistance of gar1-1, which was confirmed by three additional CRISPR/Cas9-edited gar1 alleles. GLUTAMINE SYNTHETASE 1;1 (OsGS1;1) and GLUTAMINE SYNTHETASE 1;2 (OsGS1;2) were upregulated in gar1-1 upon glufosinate ammonium treatment, directly contributing to increased GS activity that enhances glufosinate ammonium herbicide resistance. We further show that OsARF18 suppresses OsGS1;1 and OsGS1;2 expression. Comparative transcriptomic analyses reveal a huge shift in the gene expression profile involved in stress tolerance and growth. A large number of detoxification-related genes are enriched in gar1-1, which may also contribute to enhanced herbicide resistance. Moreover, stress tolerance-related genes are upregulated and growth-related genes are downregulated in gar1-1, consistent with the improved tolerance to salt and osmotic stress of gar1 mutants. Taken together, our study demonstrates that OsARF18 is a negative regulator of glufosinate ammonium resistance as well as salt and osmotic stress tolerance, suggesting a role in balancing the stress response and growth.

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Xia, J.-Q., He, D.-Y., Zhao, P.-X., Xiang, C.. 2023-06-07. Loss of OsARF18 confers glufosinate ammonium herbicide resistance in rice. https://doi.org/10.1101/2023.06.05.543806

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