Is Tuber melanosporum colonizing the roots of herbaceous, non-ectomycorrhizal plants?

The ectomycorrhizal Tuber melanosporum forms edible fruit-bodies after mating between two haploid parents: a maternal individual, which feeds the fruit-body and colonizes surrounding ectomycorrhizas, and a paternal one hitherto undetected around fruit-bodies. Several other aspects of T melanosporum ecology remain unclear, such as the formation of a bride around the mycelium, i.e. patches where plant growth is impaired. Here, we test the hypothesis that T melanosporum, and specifically paternal individuals, is present on the roots of herbaceous, non-ectomycorrhizal plants of the bride. Specific primers detected T. melanosporum on 78.9% of the plant individuals investigated (89.7% of the 80 species considered), and metabarcoding confirmed its presence on 46 of the 70 plant individuals investigated. Genotyping with 13 microsatellites detected maternal individuals of nearby fruit-bodies, but not paternal individuals, whose niche thus remains elusive. We discuss the possibility that T melanosporum is also a root endophyte in non-ectomycorrhizal plants. (C) 2017 Elsevier Ltd and British Mycological Society. All rights reserved.