N. Beikzadeh - Dep. of Plant Protection, Faculty of Agriculture, Ferdowsi University of Mashhad, P.O.Box: ۹۱۷۷۵-۱۱۶۳, Mashhad, Iran,
B. Jafarpour - Dep. of Plant Protection, Faculty of Agriculture, Ferdowsi University of Mashhad, P.O.Box: ۹۱۷۷۵-۱۱۶۳, Mashhad, Iran,
H. Rouhani - Dep. of Plant Protection, Faculty of Agriculture, Ferdowsi University of Mashhad, P.O.Box: ۹۱۷۷۵-۱۱۶۳, Mashhad, Iran,
D. Peters - Laboratory of Virology, Department of Plant Sciences, Wageningen University, Droevendaalsesteeg ۱, ۶۷۰۸ PB Wageningen, the Netherlands
A. Hassani-Mehraban - Laboratory of Virology, Department of Plant Sciences, Wageningen University, Droevendaalsesteeg ۱, ۶۷۰۸ PB Wageningen, the Netherlands

Viral symptoms indicative of Iris yellow spot virus (IYSV) were observed on onion in several fields near Chenaran in Khorasan Razavi Province. Mechanical inoculation of herbaceous hosts with onion sap extracts from symptomatic plants showed similar symptoms to those described for IYSV. The mechanically transmitted virus reacted only with antisera specific to IYSV in DAS-ELISA but not with antisera specific to seven other tospoviruses. In RT-PCR, a DNA fragment approximately ۸۲۲ bp in size was amplified from infected Nicotiana benthamiana by using primers specific to the nucleocapsid (N) gene of IYSV. After cloning and sequencing, the deduced N protein sequence of two isolates (GenBank accession no. HQ۱۴۸۱۷۳ and HQ۱۴۸۱۷۴) showed ۹۸% amino acid identity with a Sri Lankan isolate, ۹۶% with a Dutch isolate and ۹۲% with a Brazilian isolate. To our knowledge, this is the first molecular characterization of IYSV in Iran.

Iran, Iris yellow spot virus, Molecular diagnosis, Onion