Identification of host plants and description of sclerotia of the truffle Mattirolomyces terfezioides

The truffle, Mattirolomyces terfezioides, is a hypogeous ascomycete with uncertain host relationships. The fungus has been regularly collected on sandy soils in the Carpathian Basin. During the study of the natural host plants of the fungus, strange, amorphous, belowground hyphal aggregates incorporating soil and sand particles have been found attached to the surface of the roots. The fruitbodies of M. terfezioides develop from these hyphal aggregates. This structure, similar to that formed by morels, could be interpreted as a sclerotium. Sclerotia were found both on roots of woody and herbaceous plants. To detect the roots colonized by M. terfezioides, a species-specific polymerase chain reaction was developed. Seven natural hosts of the fungus were identified by this method. No specificity regarding taxa or life form of the plants was found. The colonization of the roots by the septate hyphae of M. terfezioides was weak, particularly compared to the colonization by arbuscular-mycorrhizal fungi. This suggests that this fungus is not the dominant fungal partner of these plants. Therefore, using M. terfezioides as the only inoculum may be inappropriate in truffle cultivation experiments. Nevertheless, further in vitro experiments are needed to develop reliable knowledge on the still ambiguous symbiotic strategy of this fungus.