Identification and Distribution of Onion yellow dwarf virus by Serologic and Molecular Methods in North and Razavi Khorasan Provinces

In order to detect Onion yellow dwarf virus in Khorasan province in Iran، onion samples from major onion growing regions where collected in spring and summer 2010. To determine the distribution of the virus، samples were randomly taken from onion fields in vicinity of Mashhad، Chenaran، Quchan، Torbate Heydarye، Neyshabur، Bardaskan، Gonabad، Fariman، Faruj، Shirvan، Bojnourd and Ash khane have been tested by DAS- ELISA method. Leaf samples showing mosaic، yellowing، rolling symptoms and complexity associated with dwarf onion bulbs glands were collected. Infection of samples with Onion yellow dwarf virus were confirmed using DAS-ELISA and RT-PCR tests. Total RNA was extracted from infected samples using RNX ™ (plus) kit. To perform RT-PCR test cDNA was made and then PCR test was carried out. 1. 5% Agarose gel electrophoresis of PCR products resulted in a fragment of 291 bp from CP of the virus. Amplified fragment were then sequenced. The virulence of the virus in greenhouse on three Chenopodium species (Chenopodium album، C. quinoa، C. amaranticolor) was confirmed. The results showed that onion field in Chenaran، Gonabad and Neyshabour infected with Onion yellow dwarf virus but no infection in other places.