Protozoa stimulate N uptake and growth of arbuscular mycorrhizal plants

Highlights

Arbuscular mycorrhizal (AM) fungi co-occur with protozoa in virtually any soil.
Interactive effects of AM fungi and protozoa on plant growth are little known.
Plant carbon allocation to the rhizosphere improved functioning of root symbionts.
Plant growth and N uptake via mycorrhizal symbiosis strongly benefit from protozoa.