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10.1094/PDIS-91-8-1055A]



First report of _Potato spindle tuber viroid_ in tomato in Belgium

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During August 2006, a sample of a tomato plant (_Solanum 

lycopersicum_, formerly _Lycopersicum esculentum_) from a greenhouse 

in Belgium was received for diagnosis. The plant showed severe growth 

reduction and the young leaves were chlorotic and distorted. In the 

greenhouse, the disease had been spreading slowly along the row.



These observations suggested the presence of a viroid infection, and 

reverse transcriptase (RT)-PCR [polymerase chain reaction] for 

pospiviroids yielded a positive result (amplicons of approximately 

196 and 360 base pairs). Sequence analysis of the larger amplicon 

[PCR product] revealed that the genome was 358 nucleotides and 100 

percent identical to 2 previously published isolates of _Potato 

spindle tuber viroid_ (PSTVd) from the United Kingdom and Australia. 

A pathogen associated with the symptomatic tomato plants was 

therefore identified as PSTVd.



Tracing the origin of the infection revealed the following 

from seed by a Dutch nursery were transferred to a small part of the 

greenhouse of the Belgian grower; 7 to 8 weeks later, the plants were 

transplanted to their final destination; during May 2006, the grower 

first observed growth reduction in a single plant; several weeks 

later, similar symptoms were observed in 2 more plants in the same 

row close to the 1st symptomatic plant; and by September [2006], 

there were approximately 20 symptomatic tomato plants, all located in 

2 adjacent rows.



The viroid outbreak was fully eradicated by destroying all tomato 

plants in the affected rows as well as in 2 adjacent rows at both 

sides. The absence of further infections was confirmed by testing 

approximately 1200 tomato plants in pooled samples for PSTVd by 

RT-PCR (2) and real-time RT-PCR (1). The origin and the method of 

introduction and spread of the viroid remain unclear.





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[_Potato spindle tuber viroid_ (PSTVd; type member of genus 

_Pospiviroid_) is an important pathogen of solanaceous crops, causing 

the diseases 'spindle tuber' in potato and 'bunchy top' in tomato. 

Yield losses can be up to 65 percent in potato and as much as 50 

percent in tomato. Symptoms in tomatoes include stunting, leaf 

chlorosis and distortion, and shortening of internodes. All varieties 

of tomato and potato appear to be susceptible, with no natural 

resistance to PSTVd available in either host. Other solanaceous crop 

and weed species are also susceptible to PSTVd.



Spread occurs via infected plants or plant parts, seed, pollen, 

mechanical means, or plant-to-plant contact. Only in the presence of 

_Potato leafroll virus_ (PLRV; genus _Polerovirus_), PSTVd can also 

be transmitted by an aphid vector (_Myzus persicae_). PSTVd (like 

viroids in general) is exceptionally stable due to its molecular 

structure and can survive in sap or leaf litter for considerable time.



PSTVd has been found in many countries around the world, including 

parts of North and South America, Asia, and Oceania. The pathogen is 

not endemic to Western Europe, but in recent years outbreaks have 

been reported in France, UK, Germany, and the Netherlands. In 

addition, the disease is established in Eastern Europe, including for 

example Poland and Russia. The European Plant Protection Organisation 

(EPPO) has therefore listed PSTVd as an A2 quarantine pathogen.



Maps



Pictures



Links



2004

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Potato spindle tuber viroid, tomato - Germany 20040630.1738

Potato spindle tuber viroid, tomato - United Kingdom 20040117.0179

2003

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Potato spindle tuber viroid, tomato - United Kingdom 20030909.2268

Potato spindle tuber viroid, eradication - France 20030814.2021

Potato spindle tuber, tomato - Australia (NSW) (02) 20030620.1516

Potato spindle tuber, tomato - Australia (NSW) 20030618.1506

2002

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Potato spindle tuber viroid, potato - France 20021011.5520

2001

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Potato spindle tuber viroid, tomatoes - Australia 20010622.1186

Potato spindle tuber viroid - New Zealand 20010314.0514

2000

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Potato spindle tuber viroid - Costa Rica 20000221.0236

1999

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Plant pathogens, intercepts, EPPO 19991125.2088]

...................................dha/mj/mpp