BIOLOGICAL AND MOLECULAR CHARACTERIZATION OF TOMATO SPOTTED WILT VIRUS IN ISRAEL

Symptoms resembling tomato spotted wilt virus (TSWV) infections were d ocumented among ornamental and vegetable crops in commercial greenhous es and open fields in Israel. Plants exhibiting these symptoms were co llected from January 1992 to December 1996. Among cultivated plants an alyzed for TSWV by enzyme-linked immunosorbent assay (ELISA), 19 speci es representing five families were found to be infected; natural infec tion was also recorded in six plant species of weeds. Virus identity w as characterized by host range, serology and electron microscopy. Sero logical reaction with the isolates, found in Israel, using antisera fr om different sources as well as the sequence analysis of the nucleocap sid gene, demonstrated that the Israeli isolates of TSWV are a member of tospovirus serogroup I, type I (BR-01 strain). No virus transmissio n was found in seeds collected from virus-infected vegetable and ornam ental crops. A non-radioactive molecular probe derived from the cloned nucleocapsid isolate enables specific detection of the virus in crude sap from infected plants. The detection of TSWV in Israel constitutes a severe potential threat to the ornamental and vegetable industry.