The mutation Asp-376-Glu in the ALS gene confers resistance to mesosulfuron-methyl in Beckmannia syzigachne.

Understanding the mechanisms by which weeds develop herbicide resistance is crucial for managing resistance effectively and optimizing herbicide use. Beckmannia syzigachne, a harmful grass weed prevalent in wheat and rice-wheat rotation areas, poses a significant threat to crop productivity. A field herbicide resistance survey identified a resistant population with a new ALS mutation (Asp-376-Glu). The Glu-376-Asp population displayed varying resistance levels to seven ALS herbicides, verified using the dCAPS method. qRT-PCR analysis showed that no significant difference existed in the ALS gene expression between the Asp-376-Glu and S populations. P450 and GST inhibitors failed to reverse resistance to mesosulfuron-methyl, suggesting no involvement of P450- and GST-based metabolic resistance. Molecular docking indicated that the Asp-376-Glu mutation reduces the binding affinity between ALS-inhibitors and BsALS. The findings provide valuable insights into herbicide resistance mechanisms for weed resistance control.