The Genetic Basis of the Incompatibility Reaction following Plasmodial Fusion between Different Strains of the Myxomycete Physarum polycephalum

SUMMARY: Post-fusion incompatibility among plasmodia derived from Physarum polycephalum strain 29 is controlled by interactions between alleles at three loci, two of which are linked. A reaction will occur between a plasmodium which is heterozygous or a homozygous dominant at a locus, and one which is a homozygous recessive at the same locus. Depending on genotype with respect to the three loci, incompatibility reactions among plasmodia can be absent, unilateral or bilateral.