Dominance of ultraviolet radiation resistance in partial diploids of Escherichia coli K-12.

Although an F'13 capR(+)/capR9 strain is nonmucoid and an F'13 capR9/capR(+) strain is mucoid, both strains are ultraviolet (UV)-resistant. In contrast, haploid capR9 strains are UV-sensitive. Therefore, UV resistance is dominant to UV sensitivity, regardless of whether the capR(+) allele is on the chromosome or on the F'13 episome.