Pittosporum tobira: A New Host for Tomato spotted wilt virus.

In July 1998, Pittosporum tobira shrubs, grown in a nursery in the Sharon Valley of Israel, developed foliar ring spots, mild mosaic, and tip necrosis. Of 15 samples tested for the presence of Tomato spotted wilt virus (TSWV) with a commercially available enzyme-linked immunosorbent assay (ELISA) kit (Loewe Biochemica, Otterfing, Germany), 14 were positive for TSWV. Virus in crude sap extracted from symptomatic tissue was mechanically transmitted to Emilia spp., Petunia hybrida, Nicotiana glutinosa, N. benthamiana, and N. rustica plants, which developed symptoms characteristic of TSWV infection (1). ELISA tests of leaf sap extracted from naturally infected P. tobira and mechanically inoculated indicator plants gave a strong positive reaction to TSWV. Leaf samples of P. tobira were analyzed by transmission electron microscopy in leaf-dip preparations and thin sections of leaf tissues. Virus particles typical of a tospovirus were observed only in samples taken from symptomatic leaves. Primers specific to the nucleocapsid gene of TSWV were used in a reverse transcription-polymerase chain reaction (RT-PCR) assay to verify the presence of TSWV. RT-PCR gave an expected PCR product of ≈850 bp. The amplicon was cloned in the pGEM-T vector, and the recombinant clone was sequenced. The sequence of the cloned PCR product confirmed the identity of TSWV, verifying TSWV infection of P. tobira. This is the first report of infection of P. tobira by TSWV. Reference: (1) Y. Antignus et al. Phytoparasitica 25:319, 1997.