Stijger, C.C.M.M.

Vlugt, R.A.A., van der

Vlugt, van der, R.A.A.

NARCIS 

Pepino Mosaic Virus. Research reveals variability

Name not available

Wageningen Yield 

The original pepino mosaic virus (PepMV), first found in 1974 in
Peru on pepino plants (Solanum muricatum) could in experiments
also infect tomatoes. This remained unnoticed for a long time
until the virus suddenly manifested itself in 1999 on tomato crops
in the Netherlands and the UK. It remains unclear where the virus
had hidden itself since 1974 although recent research has shown
that wild Lycopersicon species in South-America are infected with
the virus. In most cases these wild plants do not show any symp-
toms when infected with the virus.
Large distances
Fruits harvested from infected commercial tomato plants contain a
high concentration of the virus. In this way the virus can spread
quickly and unnoticed over large distances. Although it cannot be
proven, this seems the most likely route the virus followed to
Europe. Fruits showing distinct symptoms in supermarkets during
the wintertime strongly support this theory.
One of the most important reasons why the virus so quickly estab-
lished itself in certain parts of Europe is that it spreads easily.
Once attached to hands or clothes through contact with infected
plants, plant parts or fruits, the virus remains infectious for a long
time. It can spread unnoticed to for instance doorknobs and then
uninfected tomato crops.
Viruses can change
Viruses are opportunistic pathogens which can easily adapt to new
circumstances. This occurs naturally when they produce off-
spring. During every cycle, new virus particles are formed and
genetic variation is introduced. Viruses that have the correct
genetic make-up for a given situation will multiply more quickly.
During this process new and possibly more severe variants of the
virus are formed. Under the right circumstances these can quickly
become a problem. Remember that the SARS virus became a
worldwide epidemic in only a matter of weeks.
PepMV is reported in a growing number of countries worldwide
(Spain, North-America, Canada and even China). Most of these
reports are based on serological tests. But also isolates of PepMV
are described that are genetically distinct from the common
‘tomato-strain’. Such a deviant isolate was already described in
Spain in 2002. Also in North-America PepMV isolates occur that
not only differ from the European isolate but also from each other.
This could mean that the virus has taken different routes from
Peru, not only to Europe but also to North-America.
Variations in symptoms
Different opinions on the dangers of PepMV exist. Some coun-
tries report serious damage and economic losses resulting from
PepMV in tomatoes. In other countries the damage reported is
minimal. From Canada serious symptoms on infected plants like
necrosis on leaves and stems are reported, especially on plants
that receive more shade. Light apparently plays a role in symptom
expression. Whether the diverse symptoms reported from different
countries or even different cultivation sites are due to different
variants or strains of the virus is not yet known.
The combined research of Plant Research
International in Wageningen1 and Applied
Plant Research in Naaldwijk2 focuses on the
genetic variability of the virus. The main
aim is to determine if and how the virus can
adapt and what variants of the virus occur
in Europe and the rest of the world. □
1Plant Research International BV., PO Box 16, 6700 AA
Wageningen, The Netherlands. 2Applied Plant Research,
Research unit Glasshouse Horticulture, PO Box 8, 2670
AA Naaldwijk, The Netherlands
32 - Prophyta Annual 2005
PEPINO MOSAIC VIRUS
Research reveals variability
Pepino mosaic virus spreads very easily. For this reason the tomato strain of this plant virus firmly established
itself in Europe in a very short time. It remains to be seen, however, whether the same virus strain is involved on all
infected tomato cultivation sites.
René van der Vlugt1 and Ineke Stijger2
Pepino mosaic virus damage on the leaves, and stems of tomato plants.


Pepino Mosaic Virus. Research reveals variability

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