Linkage analysis of developmental mutations in aggregation-deficient mutants of Dictyostelium discoideum

Simple parasexual genetic techniques have been employed to extend the linkage analysis initiated in an earlier study (Coukell, 1975) of developmental mutations (agg mutations) in 40 independently isolated aggregation-deficient mutants of Dictyostelium discoideum. Using these techniques, agg mutations in 28 of the 40 mutants have been assigned to 4 linkage groups: 16 in group II, 1 in group III, 10 in group IV, and 1 in group VI. None of the agg mutations analyzed appear to map in linkage group I. In addition, a new temperature-sensitive growth locus, designated tsgJ, was mapped in group III. It was also found that diploid strains of D. discoideum are readily induced to undergo haploidization when grown on 0.1% p-fluorophenylalanine (PFP) at 25.5 degrees C. Growth of diploid strains on PFP had no effect on the type of segregant classes obtained (i.e. PFP does not induce mitotic crossing-over), the subsequent growth and/or development of the segregants, or the ability of the segregants to reform stable diploids.