Occurrence of iris yellow spot virus from onion crops in Egypt.

Iris yellow spot virus (IYSV) is a infects onion bulb and seed crops in many countries including Egypt. Results of the mechanical inoculation reveled that, small chlorotic lesions and systemic necrosis were observed on both Nicotiana benthamiana and Datura stramonium after 10 days, while there were no symptoms were appeared on the onion plant. The viral biological transmission with Thrips tabaci was highly reported to be efficiently for virus transmitted. Our results confirmed the presentence of virus-like particles of a Tospovirus infected onion leaf using transmission electron microscopy. Both of sequence and phylogenetic analysis of N gene revealed that our viral isolate is IYSV with 95 % identity with reported Israel isolate. The sequence of N gene had three motifs: casein kinase II Phosphorylation site, N-myristoylation site and protein kinase C phosphorylation site. These motifs are involved in regulation, activity and stability of IYSV. To our knowledge, this is the first molecular characterization of IYSV in Egypt.