A different mutation (SMR1B) to SMR1-410 (ilv2), which determines resistance to sulfometuron methyl in Saccharomyces cerevisiae, was cloned by PCR. Sequence analysis indicated a C to T change at position 575 of the ILV2 coding sequence, which results in a proline transition to leucine at position 192. Similarly to SMR1-410, the SMR1B gene was confirmed as a convenient dominant selective marker for yeast transformation including industrial strains.