Symbiotic germination and development of the myco-heterotroph Monotropa hypopitys in nature and its requirement for locally distributed Tricholoma spp

Abstract

• Germination and symbiotic development of the myco-heterotrophic plant Monotropa hypopitys were studied by sequential recovery of packets of seed buried in dune slacks in relation to distance from mature M. hypopitys and presence and absence of shoots of its autotrophic coassociate Salix repens. • Fungal associates of M. hypopitys growing under S. repens in the dune slacks, and under S. caprea and Pinus sylvestris at two other locations in the UK, were identified by molecular analysis. • While the earliest stage of germination could be found in the absence both of mature M. hypopitys, and S. repens, further development was dependent upon mycorrhizal colonisation, which was most common close to these plants. Molecular analysis showed that when growing with Salix, M. hypopitys associated with the Salix-specific ectomycorrhizal fungus Tricholoma cingulatum, whereas under Pinus it was colonised by the closely related, Pinaceae-specific, T. terreum. • We establish the first definitive chronology of development of M. hypopitys and highlight its critical dependence upon, and specificity for, locally distributed Tricholoma species that link the myco-heterotroph to its autotrophic coassociates.

Keywords: Monotropaceae; Tricholoma; fungal specificity; in situ germination; myco-heterotrophy; seedling development.