A LuALS Mutation with High Sulfonylurea Herbicide Resistance in Linum usitatissimum L.

The cultivation of herbicide-resistant crops is an effective tool for weed management in agriculture. Weed control in flax (Linum usitatissimum L.) remains challenging due to the lack of available herbicide-resistant cultivars. In this study, a mutant resistant to acetolactate synthase (ALS)-inhibiting herbicides was obtained by ethyl methanesulphonate (EMS) mutagenesis using an elite cultivar, Longya10. Whole-plant dose-response assays revealed that, compared to Longya10, the mutant was 11.57-fold more resistant to tribenuron-methyl (TBM) and slightly resistant to imazethapyr (resistance index (mutant/Longya10) < 3). In vitro acetolactate synthase assays showed that the relative resistance of the mutant was 12.63 times more than that of Longya10. A biochemical analysis indicated that there was a Pro197Ser (relative to the Arabidopsis thaliana ALS sequence) substitution within the LuALS1, conferring high resistance to sulfonylurea herbicides in the mutant. Additionally, two cleaved amplified polymorphic sequence (CAPS) markers, BsaI-LuALS1 and EcoO109I-LuALS1, were developed based on the mutation site for marker assistant selection in breeding. Moreover, the mutant did not cause losses in natural field conditions. We find a mutant with ALS-inhibiting herbicide resistance chemically induced by EMS mutagenesis, providing a valuable germplasm for breeding herbicide-resistant flax varieties.

Automated summary

In this study, a mutant with resistance to ALS-inhibiting herbicides was obtained from the elite cultivar Longya10 through EMS mutagenesis. The mutant showed significantly increased resistance to TBM and slight resistance to imazethapyr compared to Longya10. Biochemical analysis revealed a Pro197Ser mutation in the LuALS1 gene, which conferred high resistance to sulfonylurea herbicides in the mutant. Two CAPS markers were developed based on this mutation site for marker assistant selection in breeding. The mutant did not cause yield losses in natural field conditions, making it a valuable germplasm resource for breeding herbicide-resistant flax varieties.