The invention provides nucleic acids encoding mutants of the acetohydroxyacidsynthase (AHAS) large subunit comprising at least two mutations, for exampledouble and triple mutants, which are useful for producing transgenic or non-transgenicplants with improved levels of tolerance to AHAS-inhibiting herbicides. Theinvention also provides expression vectors, cells, plants comprising the polynucleotidesencoding the AHAS large subunit double and triple mutants, plants comprisingtwo or more AHAS large subunit single mutant polypeptides, and methods for makingand using the same.
