Date: April 23, 2007
From: The American Phytopathological Society (APS), Plant
Disease [edited] <http://www.apsnet.org/pd/searchnotes/2007/PDIS-91-4-0469C.asp>
First described in the early 1930s, the limited distribution of
potato "gothic" disease made it of little economic significance
in European Russia until the early 1970s when meristem-tip
culture was widely adopted throughout the former USSR to
increase production of virus-free seed potatoes. Shortly
thereafter, the yield and quality of Russian seed potatoes began
a dramatic decline. Symptoms of potato "gothic" resemble those
of _Potato spindle tuber viroid_ (PSTVd) (3), and initial
suspicions that in vitro plantlets and seed potatoes might be
viroid-infected were later proved correct when Kastalyeva et al
(2) showed that approximately 50 to 70 percent of in vitro
plantlets and tubers collected from different regions of Russia
as well as the in vitro germplasm collection maintained by the
All-Russian Potato Research Institute (ARPRI, VNIIF) were
infected with PSTVd. Measures have since been taken to reduce
the incidence of PSTVd infection, and numerous PSTVd isolates
were collected from territories of the former USSR; however,
none of these isolates have been characterized at the molecular
level.
Four PSTVd isolates maintained in field-grown tubers at the
VNIIF were subjected to sequence analysis. This revealed the
presence of 4 previously unknown PSTVd variants. All 4 tubers
were also infected with _Potato virus M_ and _Potato virus Y_
and one tuber also contained _Potato virus S_. Tests for _Potato
leaf roll virus_ were negative. Each isolate appeared to contain
only a single nucleotide variant differing from
PSTVd-intermediate strain at 2-5 positions.
The 3 closely related variants originating from Leningradskaya
Province (Northwest Russia) contained 2 to 3 nucleotide changes
and induced intermediate symptoms in Rutgers tomato. The 4th
variant originating from Samarskaya Province (Volga River
Region) contained additional changes and induced mild symptoms.
Minor differences among the Leningradskaya variants may
represent sequence drift during extended (9-11 years) tuber
passage. The presence of additional sequence changes in the
variant from Samarskaya is consistent with independent origin
and/or prolonged separation. Additional studies with a wider
range of Russian isolates of PSTVd are currently underway to
develop diagnostic methods suitable for future large-scale
screening programs.
References:
1. Y. Hu et al. Virology 219:45, 1997.
2. T. B. Kastalyeva et al. Vestn. RASKHN 3:22, 1992.
3. Y. A. Leontyeva: Potato spindle tuber ("gothic") as one of
the most important diseases in the Volga region. (In Russian)
Ph.D.
thesis. Agricultural University of Leningrad, Pushkin, 1971.
[Byline: T. Kastalyeva, K. Mozhaeva, et al]
--
Communicated by:
ProMED-mail <promed@promedmail.org>
[PSTVd affects solanaceous crops causing severe losses in potato
(up to 65 percent) and tomato (up to 50 percent). Resistant
cultivars are not available. In the EU it is listed as an A1
quarantine pathogen.
Spread occurs via infected tubers or plants, seed, pollen,
mechanical means, or plant-to-plant contact. Only in the
presence of _Potato leaf roll virus_ it can also be transmitted
by an aphid vector (_Myzus persicae_).
Meristem tip culture is a form of tissue culture that has been
used to obtain virus-free material for plant propagation.
Intra-cellular plant pathogens -- such as viruses and viroids --
spread from cell to cell and newly formed cells in the meristem
will be invaded. If the meristem is removed from the older
infected cells before the pathogen has spread, virus/viroid-free
cell lines can be obtained. However, it is necessary to verify
the virus/viroid free status of the resulting lines. For PSTVd,
more than 50 percent of resulting plantlets were found to be
viroid-free when cold-treatment (6 months at 6-8 deg C
(43-46 deg F) preceded meristem tip culture (Lizarraga et al
1980; Phytopath. 70, 754).
'Novel' in this context means 'taxonomically new'. A novel
strain of a known pathogen can vary in important disease aspects
such as type of symptoms induced and host range. In many cases
just a few nucleotide changes have been found to lead to major
changes in the pathogen/host interaction. This stresses the
importance of biosecurity even for pathogens that are already
present in a certain area since there may be strains of
increased virulence imported from elsewhere. On the other hand,
mild strains or strains which induce no symptoms at all can be
used in some instances for protecting host plants from infection
with severe strains.
A map of the worldwide distribution of PSTVd is available at <http://www.eppo.org/QUARANTINE/virus/PSTVd/PSTVD0_map.htm>
Pictures:
<http://www.forestryimages.org/browse/subimages.cfm?SUB=11936>
Leaf symptoms on potato:
<http://www.omafra.gov.on.ca/english/crops/facts/98-02514.jpg>
Affected potato tubers:
<http://vegetablemdonline.ppath.cornell.edu/Images/Potatoes/PotatoViruses/PotatoVirusfs7.jpg>
A description of PSTVd can be found at
<http://www.ictvdb.rothamsted.ac.uk/ICTVdB/index.htm>
Information on PSTVd infection of crops is available at <http://www.defra.gov.uk/planth/pestnote/pstv.htm>
Plant Disease, latest issue: <http://www.apsnet.org/pd/current/>.
- Mod.DHA]
[see also
in the
archive:
2004
----
Potato spindle tuber viroid, tomato - Germany 20040630.1738
Potato spindle tuber viroid, tomato - United Kingdom
20040117.0179
2003
----
Potato spindle tuber viroid, tomato - United Kingdom
20030909.2268 Potato spindle tuber viroid, eradication - France
20030814.2021 Potato spindle tuber viroid - Canada: eradication
20030806.1928 Potato spindle tuber, tomato - Australia:
eradication 20030804.1913 Potato spindle tuber, tomato -
Australia (NSW) (02) 20030620.1516 Potato spindle tuber, tomato
- Australia (NSW) 20030618.1506
2002
----
Potato spindle tuber viroid, potato - France 20021011.5520
2001
----
Potato spindle tuber viroid, tomatoes - Australia 20010622.1186
Potato spindle tuber viroid - New Zealand 20010314.0514 2000
----
Potato spindle tuber viroid - Costa Rica 20000221.0236]
