Genetic Control of Fertility in Streptomyces coelicolor A3(2): Plasmid Involvement in the Interconversion of UF and IF Strains

Abstract

SUMMARY: if (Initial Fertility) strains of Streptomyces coelicolor A3(2) are shown to harbour a plasmid (SCP 1). Loss of SCP 1 results in a change of fertility from if to the previously described uf (Ultra-Fertile) type. Although uf × if crosses yield recombinants for chromosomal markers with a frequency of the order of 10−5 of the total progeny, virtually all the progeny carrying the markers of the uf parent are converted to if, by reinfection with SCP 1. Efficient conversion of uf to if in such crosses is associated with the development of aerial mycelium. It is inferred that SCP 1 is responsible for the production of a diffusible substance by if strains, which prevents the development of aerial mycelium by uf strains.