© Benaki Phytopathological Institute
Hellenic Plant Protection Journal - Special Issue
42
University of Thessaloniki, School of Agriculture, Plant Pathology laboratory, GR-541
24 Thessaloniki, Greece
During 2005-2012, an extensive survey was
conducted in Cyprus, on Crete, the Dode-
canese and the Ionian islands, as well as on
mainland Greece, in order to identify the vi-
rus species and
Bemisia tabaci
biotypes in-
volved in Tomato yellow leaf curl disease
(TYLCD) epidemics. Approximately 8000
symptomatic tomato samples, 4500 weeds
and 3000 whitefly samples were collected
and analyzed. The host range of TYLCV and
TYLCSV isolates was studied using whitefly
transmission tests in several plant species.
Transmission efficiency of TYLCV and TYL-
CSV was evaluated using different
B. tabaci
biotypes colonies which harboured different
bacterial endosymbionts. Results showed
that in Greece, TYLCV was the most preva-
lent
Begomovirus
species (94.5%), whereas
TYLCSV was found in 4.5% of the total sam-
ples tested. In Cyprus, TYLCV was the only
species found to be associated with TYLCD.
Molecular identification of
B. tabaci
biotypes
showed that Q was the only biotype found
in the mainland of Greece, Peloponnese and
on the island of Crete. Both biotypes (B and
Q) are involved in TYLCD spread in Cyprus
and the Dodecanese islands. Forty nine dif-
ferent weed species belonging to 15 botan-
ical families tested positive to TYLCV under
field conditions, suggesting that the host
range of the virus is far more extensive that
previously documented. Transmission stud-
ies showed that TYLCV isolates had a broad-
er host range as well as a higher transmis-
sion efficiency than TYLCSV. Finally, TYLCV
transmission was somehow correlated with
the presence of
Hamiltonella
sp. within the
body of the
B. tabaci
insect, as colonies that
harboured this bacterium transmitted the
virus more efficiently both from and to to-
mato plants.
Citrus tristeza virus
on the island of Crete: a survey and detection protocol
applications
M. S
HEGANI
1
, D. T
SIKOU
1
, A. V
ELIMIROVIC
1
, H. A
FIFI
1
, A. K
ARAYANNI
1
, A. G
AZIVODA
1
, K. M
ANEVSKI
2
,
I. M
ANAKOS
2
and I.C. L
IVIERATOS
1
1
Plant Virology Laboratory, Sustainable Agriculture, Mediterranean Agronomic
Institute of Chania, Alsylio Agrokepion, GR-731 00, Chania, Crete, Greece.
2
Department of Geoinformation in Environmental Management, Mediterranean
Agronomic Institute of Chania, Alsylio Agrokepion, GR-731 00, Chania, Crete. Greece
Over a period of two years, more than
5,000 citrus trees were tested for the pres-
ence of
Citrus tristeza virus
(CTV) on the is-
land of Crete, resulting in thirty eight posi-
tives. Comparisons of the relative transcript
levels of CTV p23, coat protein (CP), poly-
merase (POL) and an intergenic (POL/p33)
region using quantitative RT-PCR, revealed
consistent differences in abundance for
each of these RNAs among flowers, stems,
young fruits and leaves of infected orange
trees. CTV p23 RNAs accumulated at highest
levels, reaching a maximum in the flowers,
with lower levels in the leaves, while POL
RNAs consistently accumulated at low levels
in all tissues tested. A PCR-amplified dig-la-
belled CTV p23 DNA probe was applied to
stem and leaf prints, and to crude and to-
tal RNA leaf extracts, using non isotopic hy-
bridization. This technique, when applied to
stem or leaf prints, and particularly to total
RNA, unequivocally provided strong signals
with minimal backgrounds. Moreover, an
antiserum with high sensitivity and specific-
ity of CTV detection as shown by DAS and
immunoprint ELISA was produced against
bacterially-expressed CTV CP. By the former
method, stems and flowers contained high-
er levels of CTV CP when compared to leaf
extracts. Taking into account Cretan geog-
