Transient cycloheximide resistance in a tobacco cell line

Cylcoheximide-resistant cell lines have been recovered from tissue cultures of haploid Nicotiana tabacum at the usual mutant frequency (10(-6)). One such line, CR 4/6 was studied in detail. Resistance is based on the potential of the callus to inactive cycloheximide. The transient nature of the resistance and its association with differentiated cells indicate that the new phenotype is not due to a mutation, but rather to an alteration in gene expression.