Evidence for Polygenic Control of Plasmodial Fusion in Physarum polycephalum

Abstract

THE vegetative phase of Myxomycetes (true slime moulds) is a macroscopic, multinucleate cell called a plasmodium. In many species, this structure characteristically has the capacity to migrate over solid surfaces, a feature which readily lends itself to the study of somatic compatibility. For example, when two plasmodia collide they may fuse or fail to do so, depending on whether or not they are genetically similar at certain loci^1–5. In the two species studied so far, two somewhat different explanations have been offered. For ^{Didymium iridis}, a polygenic system with simple dominance at each locus has been proposed^1–3, while a one locus, multiple allelic system with no dominance has been suggested for Physarum polycephalum^4,5.