The invention relates to methods and compositions for analyzing plant acetohydroxy acid synthase large subunit (AHASL) genes. In particular, the invention relates to methods for the detection of wild-type AHASL alleles and mutant AHASL alleles that encode imidazolinone-tolerant AHASL proteins. The methods involve the use of PCR amplification and novel compositions comprising allele-specific and gene-specific primers to detect the presence of mutant and/or wild-type alleles present at the individual AHASL genes of a plant. Specifically, the methods and compositions are useful for analyzing the three AHASL genes of Triticum aestivum and the two AHASL genes of Triticum turgidum ssp. durum.