The invention relates to mutated acetohydroxyacid synthase (AHAS) nucleic acids, expression vectors comprising the mutated nucleic acids, and proteins encoded by the mutated nucleic acids. The invention further relates to plants and seeds, respectively, which comprise an acetohydroxyacid synthase (AHAS) gene, wherein said gene encodes a mutated AHAS protein. Further provided is a method for producing an herbicide-resistant plant, a method for increasing the herbicide-resistance of a plant, and a method of controlling weeds in a field.