Identification, distribution and incidence of viruses in field-grown cucurbit crops of Iran

A survey of viruses in the major cucurbit-growing areas of 17 provinces in Iran was conducted in 2005 and 2006. A total of 1699 leaf samples were collected from melon, squash, cucumber and watermelon plants showing various virus-like symptoms. Screening for 11 cucurbit viruses by double-antibody sandwich ELISA (DAS-ELISA) or RT-PCR, found that 71% of the samples were infected by at least one virus, of which Cucurbit aphid-borne yellows virus (CABYV) was the most common overall, occurring in 49, 47, 40, and 33% of cucumber, squash, melon, and watermelon samples respectively. The second most common virus on melon and watermelon was Watermelon mosaic virus (WMV) (incidence 30–33%); on cucumber, Cucumber mosaic virus (CMV)(33%); and on squash, Zucchini yellow mosaic virus (ZYMV)(38%). To our knowledge, this is the first report of Melon necrotic spot virus (MNSV) and Zucchini yellow fl eck virus (ZYFV) in Iran. Mixed infections occurred in 49% of symptomatic samples. Mixed infections were relatively frequent in squash (58%) and melon (55%). The most frequent double infections were WMV+CABYV and ZYMV+CABYV in melon, squash and cucumber, followed by WMV+ZYMV. In watermelon, the most frequent double infection was WMV+ZYMV, followed by WMV+CABYV. The high frequency of CABYV, WMV and ZYMV in the samples assayed on all four cucurbit crops and in all areas surveyed, as well as the detection of Watermelon chlorotic stunt virus (WmCSV) and Cucumber vein yellowing virus (CVYV) in northern and southern Iran, suggest that these viruses represent a potential threat to cucurbit crops in Iran

The Spread of Tomato Yellow Leaf Curl Virus from the Middle East to the World

The ongoing global spread of Tomato yellow leaf curl virus (TYLCV; Genus Begomovirus, Family Geminiviridae) represents a serious looming threat to tomato production in all temperate parts of the world. Whereas determining where and when TYLCV movements have occurred could help curtail its spread and prevent future movements of related viruses, determining the consequences of past TYLCV movements could reveal the ecological and economic risks associated with similar viral invasions. Towards this end we applied Bayesian phylogeographic inference and recombination analyses to available TYLCV sequences (including those of 15 new Iranian full TYLCV genomes) and reconstructed a plausible history of TYLCV's diversification and movements throughout the world. In agreement with historical accounts, our results suggest that the first TYLCVs most probably arose somewhere in the Middle East between the 1930s and 1950s (with 95% highest probability density intervals 1905–1972) and that the global spread of TYLCV only began in the 1980s after the evolution of the TYLCV-Mld and -IL strains. Despite the global distribution of TYLCV we found no convincing evidence anywhere other than the Middle East and the Western Mediterranean of epidemiologically relevant TYLCV variants arising through recombination. Although the region around Iran is both the center of present day TYLCV diversity and the site of the most intensive ongoing TYLCV evolution, the evidence indicates that the region is epidemiologically isolated, which suggests that novel TYLCV variants found there are probably not direct global threats. We instead identify the Mediterranean basin as the main launch-pad of global TYLCV movements

First report of cucumber vein yellowing virus on cucumber, melon, and watermelon in Iran

International audienceSeveral viral diseases are responsible for significant economic losses in commercial cucurbit production worldwide. During a survey conducted in July 2002 in cucurbit growing areas in southern Iran, vein-clearing symptoms and leaf chlorosis on older leaves were observed on a cucumber plant near Jiroft (Kerman Province). These symptoms were similar to those caused by Cucumber vein yellowing virus (CVYV, genus Ipomovirus, family Potyviridae), a virus first described in Israel (1) and now widespread in cucurbit crops in the Middle East and Mediterranean Regions (2). The identification of CVYV was established through differential host range reaction and immunosorbent electron microscopy (IEM) experiments. Typical vein-clearing symptoms were observed following mechanical inoculation of cucumber and melon plantlets, but no symptoms were observed in Chenopodium quinoa, C. amaranticolor, Nicotiana tabacum, or Vigna sinensis. Numerous, slightly flexuous, elongated virus particles were observed in infected plant extracts. The particles were decorated by a polyclonal antiserum raised against a Sudanese isolate of CVYV. To confirm CVYV identification, total RNA extracts (TRI-Reagent, Sigma Chemical, St. Louis, MO) were obtained from the original cucumber sample. Reverse transcription-polymerase chain reactions (RT-PCR) were carried out using CVYV-specific primers CVYV-CP-5′: 5′-GCTTCTGGTTCTCAAGTGGA-3′ and CVYV-CP-3′: 5′-GATGCATCAGTTGTCAGATG-3′ designed according to the partial sequence of the coat protein gene of CVYV-Isr (GenBank Accession No. AF233429) (2). A 540-bp fragment corresponding to the central region of CVYV coat protein was obtained from extracts of infected plants but not from healthy plant extracts. Additional watermelon (n = 6) and melon (n = 4) leaf samples collected from plants growing in the same farm were tested for the presence of CVYV using RT-PCR. All samples reacted positively for CVYV. However, a sample of Citrullus colocynthis, a wild relative of watermelon growing nearby, was negative. CVYV was not detected using RT-PCR in 123 additional cucurbit samples collected from the eastern and central regions of Iran during a survey conducted in 2002. To our knowledge, this is the first report of the occurrence of CVYV in Iran. Additional surveys in southern regions where Bemisia tabaci, the vector of CVYV, is abundant are required to better estimate the prevalence of this virus in cucurbit crops in Iran