Fig 1.
Cartoon representing the phylogeny of animal pathogenic oomycetes.
The tree shows the phylogenetic position of nematode-infecting oomycetes in the context of the early diverging lineages (Haptoglossa/Eurychasma) and the 2 main oomycete clades (Saprolegnian and Peronosporalean), which all include animal pathogens. Myzocytiopsis humicola found to naturally infect Caenorhabditis elegans belongs to the Peronosporalean clade together with the plant pathogenic oomycete Phytophthora infestans and the mammalian pathogen Pythium insidiosum. The illustrations indicate the main host(s) infected by pathogen species within a certain genus, for example, nematodes in the case of Haptoglossa, brown algae for Eurychasma, and fish for Saprolegnia. Note that some genera include pathogens that infect both animal and plant hosts. The tree is adapted from [10] and modified to include nematode pathogens based on phylogenetic relationships described in [2,19].
Fig 2.
Caenorhabditis elegans infection by Myzocytiopsis humicola.
(A) Cartoon describing the oomycete life cycle within nematodes. (B) Images show different stages of the infection process from pathogen attachment (left panel, arrowhead marks M. humicola adhesive bud attached to the nematode mouth) to early hyphal growth (middle panel, pathogen is visualised in red by 18S FISH), to development of “pearl-like” sporangia in the head region (right). (C) Late infection phenotype at the whole animal level with pathogen sporangia now developed throughout the body. Scale bars are 20 μm in B and 100 μm in C.