Expression of a receptor kinase in Arabidopsis roots is stimulated by the basidiomycete Piriformospora indica and the protein accumulates in Triton X-100 insoluble plasma membrane microdomains

Piriformospora indica, an endophytic fungus of the Sebacinaceae family, colonises the roots of a wide variety of plant species and promotes their growth, in a manner similar to mycorrhizal fungi. We demonstrate that the fungus also interacts with the non-mycorrhizal host Arabidopsis thaliana. Promotion of root growth was detectable even before noticeable root colonization, and was accompanied by a massive transfer of phosphate from the media to the aerial parts of the seedlings. During the recognition period of both organisms, the message for a receptor kinase with leucine-rich repeats is transiently upregulated. The kinase is located in Triton X-100-insoluble plasma membrane microdomains. Thus, this is one of the earliest events of a plant root in response to a fungus reported to date.