Inoculation, isolation and identification of Tuber melanosporum from old and new oak hosts in Israel

Abstract

Five local oak species, Quercus boissieri, Q. calliprinus, Q. cerris, Q. ithaburensis and Q. libani were identified as hosts of Tuber melanosporum , the black truffle of Perigord, following inoculation of roots. Q. cerris and Q. libani developed abundant mycorrhizal roots, similar to the amount found in roots of Q. pubescens , the traditional host of this mycorrhizal fungus. Roots of Q. ilex, Q. hartwissiana and Q. pedunculiflora , introduced species in Israel, were also heavily colonized by the mycorrhizal fungus. Mycorrhized hazel ( Corylus avellana ) roots, were also obtained by the same inoculation procedure. Recovery of T. melanosporum from roots of inoculated oak was improved when chloramphenicol was added to the isolation medium. Recovery varied between 14 and 54% for C. avellana and Q. calliprinus , respectively. Recovery was highest for the two local species, Q. calliprinus (54%) and Q. boissieri (50%), followed by Q. pubescens (44%) and Q. ilex (41%). Identification of the isolated fungi was conducted using arbitrarily-primed PCR. Identical band patterns were observed among AP-PCR-amplified DNA extracted from an authentic culture of the fungus, ascocarps (truffles) and cultures isolated from roots. In addition, AP-PCR was reliable for differentiating between representative isolates of T. melanosporum, T. magnatum, T. borchii, T. maculatum, T. dryophilum, T. macrosporum and T. uncinatum.