ABSTRACT Fusarium subglutinans has been associated with mango floral and vegetative malformation, although confusion exists regarding the etiology of the disease. A wild-type isolate of F. subglutinans causing mango malformation disease was transformed with the GUS (beta-glucuronidase) reporter and hygromycin resistance genes. Five stable transformants were isolated containing varying copy numbers at different integration sites. Specific GUS activity was quantified for the transformants, whereas no activity was recorded for the wild-type isolate. The transformants and the wild-type isolate were inoculated into healthy mango floral and vegetative buds. Typical symptoms of misshapen shoots with short internodes, stubby leaves, and bunchy, malformed inflorescences were observed 6 to 8 weeks following inoculation. The presence of GUS-stained mycelium of the pathogen viewed microscopically within infected plant organs provided unequivocal evidence that F. subglutinans is indeed a causal agent of mango malformation disease.

Five local oak species, Quercus boissieri, Q. calliprinus, Q. cerris, Q. ithaburensis and a. libani were identified as hosts of Tuber melanosporum, the black truffle of Perigord, following inoculation of roots, a. cerris and a. 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 a. 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 a. pubescens (44%) and Q. ilex (41%). Identification of the isolated fungi was conducted using arbitrarily-primed PCR. Identical band patterns were observed among AP-FCR-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.