November 22, 2005
From:  American Phytopathological Society, Plant Disease Notes, November 2005 [edited] <http://www.apsnet.org/pd/searchnotes/2005/PD-89-1243C.asp>


First report of tomato chlorosis virus and tomato infectious chlorosis virus in tomato crops in France
A. Dalmon, S. Bouyer, and M. Cailly, Laboratoire National de la Protection des Vegetaux (LNPV), Unite de virologie des plantes herbacees, Domaine St Maurice, BP94, 84143 Montfavet cedex, France; and M. Girard, H. Lecoq, C. Desbiez, and M. Jacquemond, Institut National de la Recherche Agronomique (INRA), Station de Pathologie Vegetale, Domaine St Maurice, BP94, 84143 Montfavet cedex, France. Plant Dis. 89:1243, 2005; published on-line as DOI: 10.1094/PD-89-1243C. Accepted for publication 11 Aug 2005.

Since 2002, yellowing symptoms associated with high levels of whitefly populations have been observed in plants of protected tomato crops in France. Symptomatic plants exhibited interveinal yellowing areas in older leaves,
followed by generalized yellowing. Symptoms were not observed in young plants or fruits. _Trialeurodes vaporariorum_ populations were generally abundant in spring, and _Bemisia tabaci_ (established in France for approximately 10 years) became predominant in summer and fall.

To check for the presence of Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV), 2 whitefly-transmitted criniviruses known to induce yellowing symptoms, 696 samples were collected in the major tomato-growing areas; 573 samples from southern France and 123 samples from northern France. Total RNA was extracted from each sample and analyzed using reverse transcription-polymerase chain reaction (RT-PCR). Primers specific to ToCV (2) and TICV (1,3) were used to amplify either part of the heat-shock-like protein gene HSP70h (both viruses) or part of the diverged coat protein gene (CPd), (TICV only).

A 439-bp DNA fragment was obtained with ToCV primers in 178 samples from southern France collected mainly from mid-spring to early fall from 2002 to 2004. 3 RT-PCR products amplified from samples collected from diverse growing areas were sequenced and showed 99-100 percent sequence identity with published ToCV sequences from Spain (GenBank Accession Nos. AF215818, AF233435, and AF215817), Portugal (GenBank Accession No. AF234029), Sicily (GenBank Accession No. AY048854), and the United States (GenBank Accession No. AF024630).

Considering the high frequency of ToCV-infected samples (41 positive samples of 112 samples collected in 2002, 71 of 295 collected in 2003, and 66 of 166 collected in 2004), this virus appears to be well established in southern France but remains absent in the northern regions. The presence of TICV was tested in 485 samples using the CPd-specific primers or the HSP70h-specific primers. The virus was detected in only 2 samples from Nice (southeastern France) in 2003 with both primer pairs. The CPd DNA fragment (700 bp) from one of these samples was sequenced, showing 98.9 percent sequence identity with a TICV Japanese isolate (AB085603).

Results of these assays suggest that in contrast to ToCV, TICV is not yet broadly established in France. This difference could be associated with the specificity of the vectors, since ToCV is transmitted by _B. tabaci_ and _T.
vaporariorum_, while TICV is transmitted only by _T. vaporariorum_ (4).

References:
(1) R. H. Li et al. Plant Dis. 82:84, 1998.
(2) D. Louro et al. Eur. J. Plant Pathol. 1065:589, 2000.
(3) A. M. Vaira et al. Phytoparasitica 30:290, 2002.
(4) G. C. Wisler et al. Plant Dis. 82:271, 1998.

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[Criniviruses are an emerging genus worldwide, containing new species that have evolved over time and are now evident as causal agents of new plant diseases. Their symptoms are easily mistaken for those of physiological or
nutritional disorders or pesticide phytotoxicity, thus confounding their identification. Symptoms can vary, depending upon the host species, to include interveinal leaf yellowing, loss of photosynthetic capability, leaf
brittleness, reduced plant vigor, yield reductions and early senescence. Criniviruses remain confined to cells associated with the plant phloem and symptoms are considered to result from plugging of the phloem with large viral inclusion bodies, thus likely interfering with normal vascular transport in infected plants. Both TICV and ToCV were first reported during the 1990s in the United States, and ToCV has been reported to occur in the Mediterranean countries, Portugal, Spain, and Italy

4 crinivirus species transmitted by greenhouse white fly (GHWF) have been identified to date, including Beet pseudo yellows virus (BPYV), Strawberry pallidosis-associated virus (SPaV), ToCV and TICV. The latter viruses have  exerted significant pressure on vegetable and fruit production in North America, Europe, and other parts of the world, affecting both greenhouse-grown crops as well as field crops.

3 viruses, primarily BPYV, SPaV, and TICV, are transmitted exclusively by GHWF, and are currently responsible for economic damage to vegetable and fruit production. Although ToCV is transmitted by the GHWF and impacts tomato production, it is much more efficiently transmitted by _B. tabaci_ [Bt] biotype B than by GHWF, and its incidence is associated more closely with the presence of Bt in fields and greenhouses than with GHWF. These criniviruses have host ranges of varying size, ranging from quite narrow in the case of SPaV, to extremely broad in the case of BPYV. Although all GHWF-transmitted criniviruses infect weed species and wild relatives of cultivated crops, their primary agricultural impact occurs on 3 major groups of crops. Thus TICV and ToCV exert their main economic impact on tomato production in both greenhouse and field settings. SPaV is a problem in strawberry; BPYV, with its extensive host range, infects numerous cucurbit species, as well as strawberry and blackberry.

Disease management is straightforward; use of virus-free transplants, avoidance of susceptible hosts, especially weeds, roguing of infected plants, and control of insects by chemical insecticides.

Links:
<http://www.cnr.it/istituti/FocusByN_eng.html?cds=107&nfocus=2>
<http://www.apsnet.org/online/feature/whitefly/>
<http://www.eppo.org/QUARANTINE/virus/Tomato_chlorosis_virus/DSTOCV00.pdf> <http://www.eppo.org/QUARANTINE/Alert_List/viruses/tmicxx.htm>
- Mod.DH]

[see also in the archive:
Tomato chlorosis, tomato - France (Reunion Island): 1st report 20050605.1566
2004
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Whitefly-transmitted virus, bean - Spain 20040501.1206
2003
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Tomato infectious chlorosis, tomato - Indonesia 20030709.1676
2002
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Tomato infectious chlorosis virus, tomato - Spain 20020706.4678
Tomato criniviruses, detection - Greece 20021130.5939
2001
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Whitefly-transmitted criniviruses, virion lengths 20010524.1005
Tomato chlorosis crinivirus disease - Puerto Rico 20010324.0588
Tomato chlorosis crinivirus - Puerto Rico 20010515.0942]