Detection and geographical distribution of whitefly transmitted viruses in cucumber greenhouses in Iran

In recent years, yellowing symptoms and high population of whiteflies have been observed in many cucumber grown greenhouses in Iran. During 2011- 2012, surveys were performed in the major cucumber growing greenhouses of Tehran, Semnan, Isfahan, and Yazd provinces of Iran and a total of 287 leaf samples showing yellowing and thickening symptoms were collected. The samples were tested for the presence of whitefly-transmitted viruses (WTVs) such as Cucurbit chlorotic yellows virus (CCYV), Cucumber vein yellowing virus (CVYV) and Cucurbit yellow stunting disorder virus (CYSDV), using double/triple antibody sandwich enzyme-linked immunosorbent assay (DAS/TAS-ELISA) and reverse-transcription polymerase chain reaction (RT-PCR). The majority of the collected samples were infected by CCYV and CVYV (52 and 42%, respectively), and detected in all surveyed provinces. The least infection of samples was related to CYSDV (18%) which not detected in Isfahan province. Mixed infections were also found in 62% of the symptomatic samples. Double infection was the most mixed infection: CCYV+CVYV (49%). A 460 bp fragment of heat shock protein gene (hsp70) of three Iranian CYSDV isolates was amplified and sequenced. Phylogenetic analyses based on the nucleotide sequence of amplified fragment showed that Iranian isolates of CYSDV clustered into a separate clade than other isolates of this virus. The results of this study showed the presence of high level of WTVs infection in greenhouses associated with yellowing symptom induction.