AHAS genes and gene alleles that provide resistance to imidazolinone herbicides

Brassica juncea B. juncea B. nigra B. juncea Plants, plant parts and plant seeds that are resistant to imidazolinone herbicides are provided. Plants are disclosed that contain a mutation in an AHAS gene. Specifically, plants are disclosed that contain a mutant AHAS gene allele of the B genome. Two AHAS gene sequences (BjAHAS-a and BjAHAS-b) and one AHAS gene sequence (BngrAHAS) are disclosed. The sequence of the mutant allele, BjAHAS-bR, is also disclosed. Various methods are disclosed that include creation of mutant lines, selection for herbicide resistant lines and determining the presence of the BjAHAS-bR mutant allele after crosses.