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Among horticultural crops, ornamental plants represent the most diversified sector in terms of genetic diversity (species, cultivars) and markets (cut flowers, plants in pots or for gardens, bulbs, shrubs). In France, the value of imported ornamental plants is 14 times greater than the value of the corresponding exports. These plants can harbor viruses that could cause serious damage in more economically important species, in particular vegetable and fruit crops, and thus present a potential source of new viral diseases. Serological and molecular diagnostic tools are effective for detection of known viruses, but considering the ever increasing number of ornamental species, their rapid turnover, and the scope of their trade worldwide, it is critical to develop means to also detect plant viruses that are not current targets of sanitary surveillance in a manner as exhaustive as possible. Further, viruses under quarantine restriction are of particular concern. In this study, we present a novel strategy for detecting known and unknown viruses of various genome types, including viroids, in a diverse panel of ornamental plants.

Despite their effects on crop yield, poleroviruses are often overlooked because their symptoms, yellowing in mature leaves, may be inconspicuous or confused with nutrient deficiency. In cucurbits, the only polerovirus known for a long time…

Surveys were conducted from 2008 to 2010 to identify the viruses infecting cucurbit fields in Adana and Mersin provinces of Cukurova region in Turkey. All cucurbit samples collected from 18 districts were tested for Cucumber mosaic virus (CMV), Cucurbit aphid-borne yellow virus (CABYV), Papaya ringspot virus (PRSV), Squash mosaic virus (SqMV), Zucchini yellow mosaic virus (ZYMV) and Watermelon mosaic virus (WMV) by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) using polyclonal antisera. Overall, 449 out of 485 samples were found positive for the tested viruses; 327 out of 350 samples in Adana and 122 out of 135 in Mersin were infected at least with one virus. During the entire surveys, 258 of 281 squash samples, 33 of 33 cucumber samples, 84 of 88 melon samples and 74 of 83 watermelon samples were found to have a single or mix virus infection. All six viruses were detected on cucurbits in Adana while all samples from Mersin province were found to be negative for CABY. Sequence analyses indicated that the Turkish ZYMV isolates (ZYMV-TR3, ZYMV-TR15 and ZYMV-TR17) belong to the most common molecular cluster of ZYMV worldwide, including isolates from Europe, Africa, the Middle East, the Indian subcontinent and South America.

Surveys were conducted from 2008 to 2010 to identify the viruses infecting cucurbit fields in Adana and Mersin provinces of Cukurova region in Turkey. All cucurbit samples collected from 18 districts were tested for Cucumber mosaic virus (CMV), Cucurbit aphid-borne yellow virus (CABYV), Papaya ringspot virus (PRSV), Squash mosaic virus (SqMV), Zucchini yellow mosaic virus (ZYMV) and Watermelon mosaic virus (WMV) by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) using polyclonal antisera. Overall, 449 out of 485 samples were found positive for the tested viruses; 327 out of 350 samples in Adana and 122 out of 135 in Mersin were infected at least with one virus. During the entire surveys, 258 of 281 squash samples, 33 of 33 cucumber samples, 84 of 88 melon samples and 74 of 83 watermelon samples were found to have a single or mix virus infection. All six viruses were detected on cucurbits in Adana while all samples from Mersin province were found to be negative for CABY. Sequence analyses indicated that the Turkish ZYMV isolates (ZYMV-TR3, ZYMV-TR15 and ZYMV-TR17) belong to the most common molecular cluster of ZYMV worldwide, including isolates from Europe, Africa, the Middle East, the Indian subcontinent and South America.

In 2014, a total of 108 symptomatic watermelon samples were collected in Greece and analyzed by DAS-ELISA using polyclonal antisera (INRA, Montfavet) against the most common aphid-transmitted viruses. Cucumber mosaic virus (CMV) was detected in eight of 108 plants tested. Five of these plants collected at Lesvos were also infected with Watermelon mosaic virus (WMV), whereas three plants from Prohoma had single infections. Five samples with severe stunting and yellowing collected at Asenovgrad (Bulgaria) in 2013 and tested by DAS-ELISA for the above viruses hosted CMV and Cucurbit aphid-borne yellows virus (CABYV). To confirm CMV presence in watermelon, a nested RT-PCR assay was carried out first with the degenerated primers CMVup624a (5′-ATGGACAAATCTGRATC- 3′) and CMVdo1244a (5′-TGRTGCTCRAYGTCKACATGA-3′) followed by CMVup624b (5′-GGACAAA TCTGRA TCTCCCAA TGC-3′) and CMVdo1244b (5′- TGCTCRAYGTCRACATGAAG-3′) that amplify a 622 bp region from the viral coat protein gene. Total RNA (Chatzinasiou et al., 2010, method A) extracted from all ELISA- positive watermelon samples from both countries and from two healthy watermelon plants was used as template in nested RT-PCR. A product of the expected size was amplified from all serologically CMV-positive samples, but not from the healthy ones. The Greek CMV isolates from Lesvos (LN810059) and Prohoma (LN810060) showed 99% nucleotide sequence identity with potato (AB448694) and tomato (EF153734) CMV isolates from Syria and India, while the Bulgarian isolate (LN810058) showed 99% nucleotide sequence identity with an Indian cucumber isolate (JF279608). Phylogenetic analysis indicated that the Greek CMV isolate (LN810059) belongs to sub-group IA, while the Bulgarian isolate and a Greek isolate (LN810060) belong to sub-group IB. To our knowledge this is the first report of CMV infecting watermelons in Greece and Bulgaria.

International audience; Plant viruses are generally considered incapable of infecting vertebrates. Accordingly, they are not considered harmful for humans. However, a few studies questioned the certainty of this paradigm. Tobacco mosaic virus (TMV) RNA has been detected in human samples and TMV RNA translation has been described in animal cells. We sought to determine if TMV is detectable, persists, and remains viable in the lung tissues of mice following intratracheal inoculation, and we attempted to inoculate mouse macrophages with TMV. In the animal model, mice were intratracheally inoculated with 10(11) viral particles and were sacrificed at different time points. The virus was detected in the mouse lungs using immunohistochemistry, electron microscopy, real-time RT-PCR and sequencing, and its viability was studied with an infectivity assay on plants. In the cellular model, the culture medium of murine bone marrow derived macrophages (BMDM) was inoculated with different concentrations of TMV, and the virus was detected with real-time RT-PCR and immunofluorescence. In addition, anti-TMV antibodies were detected in mouse sera with ELISA. We showed that infectious TMV could enter and persist in mouse lungs via the intratracheal route. Over 14 days, the TMV RNA level decreased by 5 log(10) copies/ml in the mouse lungs and by 3.5 log(10) in macrophages recovered from bronchoalveolar lavage. TMV was localized to lung tissue, and its infectivity was observed on plants until 3 days after inoculation. In addition, anti-TMV antibody seroconversions were observed in the sera from mice 7 days after inoculation. In the cellular model, we observed that TMV persisted over 15 days after inoculation and it was visualized in the cytoplasm of the BMDM. This work shows that a plant virus, Tobacco mosaic virus, could persist and enter in cells in mammals, which raises questions about the potential interactions between TMV and human hosts.