Vegetative cell fusion and a new stage in the life cycle of the Aphelida (Opisthosporidia).

The aphelids, intracellular parasitoids of algae, represent a large cluster of species sister to Fungi in molecular phylogenetic trees. Sharing a common ancestor with Fungi they are very important in terms of evolution of these groups of Holomycota. Aphelid life cycle being superficially similar to that of chytridiomycetes is understudied. We have found in the aphelids a new stage - big multiflagellar and amoeboid cells, formed from a plasmodium that has two sorts of nuclei after trophic stage fusion. The families of protein-coding genes involved in the vegetative cell fusion in Opisthokonta were also discussed.