Development of ichthyosporeans sheds light on the origin of metazoan multicellularity

► Ichthyosporean Creolimax fragrantissima is a model to study the origin of multicellularity. ► We succeeded in transforming C. fragrantissima by electroporation. ► We silenced gene expression by siRNA and Morpholino in C. fragrantissima cells. ► Growing C. fragrantissima cells are syncytia where nuclei divide synchronously. ► Ichthyosporean colony formation suggests a strategy of multicellularity evolution.