April 3, 2006
From: ProMED-mail<promed@promedmail.org>
Source: American Phytopathological Society, Plant Disease Notes, April 2006 [edited] <http://www.apsnet.org/pd/searchnotes/2006/PD-90-0528A.asp>

First report of tomato apical stunt viroid in tomato in Tunisia
J. Th. J. Verhoeven, C. C. C. Jansen, and J. W. Roenhorst, Plant Protection Service, Unit Virology, P.O. Box 9102, 6700 HC Wageningen, the Netherlands. Plant Dis. 90:528, 2006; published on-line as DOI: 10.1094/PD-90-0528A. Accepted for publication 22 Jan 2006.

In May 2005, the Plant Protection Service in the Netherlands received 2 tomato (_Lycopersicon esculentum_) plant specimens for diagnosis from a protected crop production facility of 2.5 ha near Kebili in Tunisia. Growth of the plants was reduced, and leaves were chlorotic and brittle. Ripening of the fruits was delayed, and their storage life was reduced from 3 weeks to one week. The grower reported that initially only 5 percent of plants showed symptoms; however, the number of symptomatic plants increased quickly to 100 percent as a result of increasing temperatures in the production facility. Test plant species _Chenopodium quinoa_, _Datura stramonium_, _Nicotiana glutinosa_, _N. hesperis-67A_, _N. occidentalis-P1_, and _L. esculentum_ "Money-maker" were mechanically inoculated with sap from the affected plants. Symptoms including chlorosis and stunting were observed only on _L. esculentum_. Reverse transcriptase-polymerase chain reaction (RT-PCR) with universal pospiviroid primers Pospi1-RE/FW (2) yielded amplicons of the expected size (196 bp) for each of the 2 samples. One of these amplicons was sequenced and showed the highest identity to the 4 isolates of Tomato apical stunt viroid (TASVd) in the NCBI GenBank. Subsequently, the complete sequence of the Tunisian isolate (GenBank Accession No. DQ144506) was determined by sequencing the amplicon obtained after RT-PCR using primers developed for the detection of Citrus exocortis viroid (CEVd) (1). The isolate consisted of 363 nucleotides and showed the highest sequence identity (96.7 percent) to tomato isolates of TASVd from Indonesia and Israel (GenBank Accession Nos. X06390 and AY062121, respectively), 92.6 percent to a tomato isolate from the Ivory Coast (GenBank Accession No. K00818), and 87.7 percent to an isolate from Solanum pseudocapsicum (GenBank Accession No. X95293). The next highest sequence identity was 81.5 percent to an isolate of CEVd (GenBank Accession No. X53716). On the basis of these results, the viroid was identified as TASVd. To our knowledge, this is the 1st report of TASVd in Tunisia.

Reference:
(1) N. Önelge. Turkish J. Agric. For. 21:419, 1997.
(2) J. Th. J. Verhoeven et al. Eur. J. Plant Pathol. 110:823, 2004.

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ProMED-mail
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[The vegetable crop plant tomato (_Lycopersicon esculentum_) develops symptoms of the disease apical stunt when infected with tomato apical stunt viroid (family: _Pospiviroidae_, genus: _Pospiviroid_, TASVd). This report
is the 1st for TASVd in Tunisia and is from tests done on tomato samples collected from protected facilities (greenhouses/screenhouses?) in May 2005. The most recent post in ProMED-mail (20030910.2273) is a 1st report in Israel posted in 2003 for samples collected in 1999/2000. Earlier reports of TASVd (1980's) are from Indonesia and Ivory Coast. The RNA sequence of the Tunisian, Israeli and Indonesian strains are very similar.
Affected tomato plants in Israel showed shortened internodes (bushy appearance), leaf deformation and yellowing, reduced fruit size, and pale red discoloration of fruit. Up to 100 percent disease incidence could be
observed at single sites with heavy yield losses. The present article also noted 100 percent disease incidence once temperatures were high, which is a characteristic of several diseases caused by viroids. TASVd can be
transmitted from infected to healthy tomato plants by grafting or mechanical inoculation (in experimental conditions). No data is available on pollen or seed transmission, though some viroids are known to be transmitted by these means. Introduction on transplants is a strong possibility. Control of viroids is difficult in practice, so it would be desirable to avoid any further spread of a potentially serious disease of tomatoes. This new report from Tunisia acts as a warning to other countries. Other viroids that have been detected in Tunisia are noted in the archive below.

Map:
<http://www.tageo.com/index-e-ts-v-31-d-m1030709.htm>

Links:
<http://www.eppo.org/QUARANTINE/Alert_List/viruses/apicalstunt.htm>
<http://www.phytoparasitica.org/phyto/pdfs/2002/issue5.pub/ANTI.pdf>
- Mod.JAD]

[see also in the archive:
2004
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Viroids, citrus - Tunisia (Cap Bon) 20041026.2898
Fruit tree viroids - Tunisia (Sahel) 20041002.2713
2003
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EPPO Alert List: new listings (06) 20030910.2273
Australian grapevine viroid - Mediterranean region 20030830.2189]