© Benaki Phytopathological Institute
Hellenic Plant Protection Journal - Special Issue
44
the establishment of a successful potyvirus
infection, we tested the capacity of heterol-
ogous RSSs with a different mode of action
coming from animal and plant viruses to re-
place the HC-Pro. For this purpose infectivity
studies took place using recombinant infec-
tious clones of PPV which showed that the
HC-Pro of the virus can be functionally re-
placed by some but not all the RSSs studied,
including some of animal virus origin. Inter-
estingly, the capacity of a protein to replace
HCPro was not strongly associated with its
ability to suppress silencing. Overall, the re-
sults of this study show that not all RNA si-
lencing suppression strategies are equally
suitable for the effective escape of PPV and
the establishment of a successful infection.
Studies on the adaptation of
Potato virus Y
to pepper plants
N. V
ASSILAKOS
1
, V. S
IMON
2
, A. T
ZIMA
1
, O. K
EKTSIDOU
1
and B. M
OURY
2
1
Laboratory of Virology, Benaki Phytopathological Institute, St. Delta Str. 8, 14561
Kifissia, Greece.
2
INRA, UR407 Pathologie Végétale, F-84140 Montfavet, France
Potato virus Y
(PVY) isolates (genus
Potyvirus
)
are classified into four major phylogenet-
ic groups, O, N, C1 and C2. Only isolates be-
longing to group C1 are able to systemical-
ly infect pepper plants. In order to identify
the regions of PVY genome that determine
the ability of C1 isolates to infect pepper
plants, a series of full length infectious virus
clones have been constructed comprising of
hybrids between a PVY-C1 and a PVY-N or
a PVY-C2 isolate, covering in different com-
binations the entire virus genome. The in-
fectivity experiments on pepper plants us-
ing these hybrid viruses have revealed that
the major determinants of PVY infectivity on
pepper were located within the P3/PIPO and
the CI coding regions. In addition, fluores-
cent microscopy of a PVY-N isolate incorpo-
rating the GFP reporter gene showed restric-
tion of the virus to a small number of cells in
the inoculated leaves, providing a first in-
sight into the mechanism of resistance.
Further identification of virus-host protein interactions (
Pepino mosaic
virus
-tomato) and plant responses to viral infection
M.M. M
ATHIOUDAKIS
1,2
and I. L
IVIERATOS
1
1
Plant Virology Laboratory, Department of Sustainable Agriculture, Mediterranean
Agronomic Institute of Chania, Alsylio Agrokepion, GR-731 00, Chania, Crete,
Greece.
2
Plant Pathology Laboratory, Faculty of Agriculture, Aristotle University of
Thessaloniki, P.O. Box 269, GR-541 24 Thessaloniki, Greece
Pepino mosaic virus
(PepMV), belonging to
the genus
Potexvirus
, was first reported in
Peru (1980) in
Solanum muricatum
(pepi-
no). PepMV has spread over the last decade
in tomato crops throughout Europe, due
to its ready mechanical transfer and seed
transmission, and has been included on the
alert list of pathogens necessitating con-
trol strategies. Four PepMV genotypes exist
with sequence divergence that affects host
range/symptomatology and most likely also
pathogenicity as a result of specific interac-
tions with the hosts. One group of pathoge-
nicity determinants is the result of virus-host
protein interactions. We have recently iden-
tified two tomato-PepMV protein interac-
tions; Hsc70-PepMV CP, and catalase-PepMV
TGBp1 (p25) by yeast two–hybrid interac-
tion, electron microscopy and fluorescence
microscopy assays. In the present study, fur-
ther
in vivo
and
in vitro
confirmation of these
interactions is presented. Tomato responses
to PepMV infection, as revealed using mo-
lecular and biochemical methods are also
presented.
