Protists in the Plant Microbiome: An Untapped Field of Research.

Protists are mostly unicellular eukaryotes. Some protists are beneficial for plants, while others live as endosymbionts and can cause severe plant diseases. More detailed studies on plant-protist interactions exist only for plant pathogens and parasites. A number of protists live as inconspicuous endophytes and cause no visible disease symptoms, while others appear closely associated with the rhizosphere or phyllosphere of plants, but we still have only a vague understanding on their identities and functions. Here, we provide a protocol on how to assess the plant-associated protist community via Illumina-sequencing of ribosomal marker-amplicons and describe how to assign taxonomic affiliation to the obtained sequences.