Page 21 - Volume 1, Issue 1, January 2008

New plant pathogens in Greece 19
Tomato mild green mosaic virus 
(TMGMV, genus Tobamovirus)
During 2002-2003, a survey was con-
ducted to estimate the incidence of virus-
es infecting tobacco tree ( Nicotiana glauca
Graham). A total of 125 samples originat-
ing from six areas were tested serological-
ly (ELISA) and molecularly (nested RT-PCR
and RFLP analysis). The results showed re-
latively high incidence of TMGMV (19.2%),
a mechanically transmitted virus (Math-
ioudakis et al., 2006).
3.4. Viruses transmitted by other means
Parietaria mottle virus 
(PMoV, genus Ilarvirus)
A necrotic disease of tomato causing
apical necrosis, necrotic spots on the leaves,
and corky rings and brown patches on the
fruit surface was occasionally observed in
Thessaloniki and Chalkidiki in 1997. An un-
usual ilarvirus was isolated from tomato
plants, biologically and serologically related
to PMoV, now considered as a tomato strain
of PMoV (PMoV-T) (Roggero et al., 2000; Ka-
tis et al., 2001). Disease symptoms are gen-
erally observed in June to July in young
tomato plants and at the early stages of
infection are very similar to those caused
by Tomato spotted wilt virus (TSWV) or Cu-
cumber mosaic virus (CMV) carrying the
necrotic CARNA 5 satellite. Since then the
disease appears sporadically in the coun-
try without causing serious problems. No
vector of the virus is known.
Sowbane mosaic virus  (SoMV, genus
Sobemovirus), Olive mild mosaic virus
(OMMV, genus Necrovirus)
In 2004, a new virus disease inducing
mosaic and deformation in spinach oc-
curred in Marathon (Attica). Two viruses
were isolated, SoMV, which is transmitted
by seeds (up to 60% in Chenopodium qui-
noa Willd.) and probably by a vector, and a
virus recently isolated from olive with the
provisional name Olive mild mosaic virus,
for which till then the only known host
was olive (Gratsia et al., 2006).
3.5. Concluding remarks
A total of 52 new viruses and viroids
have been reported and characterized in
Greece since 1990. Twenty-six were iden-
tified on vegetable crops, 22 on fruit trees
and grapevine, two on the ornamental or-
chid, one on maize and one on a peren-
nial weed (N. glauca). Among these new-
ly reported viruses and viroids those that
represent serious threat for the country are
the following: CTV in citrus, TYLCV, TYLCSV,
ToCV, TICV in tomato, BPYV, CYSDV, CABYV
in cucurbits and PVY NTN in potato. These vi-
ruses are either aphid (CTV, CABYV, PVY NTN)
or whitefly transmitted (Begomo- and Crin-
iviruses). Aphid-borne viruses consist a
major threat for open field crops whereas
the whitefly-borne viruses for the protect-
ed ones. Whitefly transmitted viruses were
considered problematic principally in trop-
ical and subtropical countries but recently
have become real threats in the countries
of the Meditterannean basin. Production of
virus-free seedlings produced in large nurs-
ery enterprises is very important for the
control of whitefly transmitted viruses.
Among the above mentioned viruses,
two, namely CTV and PVYNTN , were clearly
introduced through importation of infect-
ed plant material from Spain and Scotland,
respectively. Although eradication mea-
sures were undertaken against CTV, the vi-
rus remains a serious threat especially in
Crete and possibly in Southern of Pelopon-
nese (Skala Lakonias) where recently de-
tected. The recent introduction of its most
efficient vector T. citricida in Europe (Portu-
gal and Spain) makes imperative the appli-
cation of strict quarantine procedures and
the continuation of eradication measures.
Vigilance is also required as far as health
certificates are concerned because it was
revealed that they do not always guaran-
tee the total absence of serious pathogens.
For this reason control tests are important