© Benaki Phytopathological Institute
Hellenic Plant Protection Journal - Special Issue
30
tomato, artichoke, rocket, among others.
This work reports the biochemical and mo-
lecular characterisation of bacterial isolates
primarily identified as
Pseudomonas viridi-
flava,
that have been maintained for the last
twenty years in the collection of Bacteriolo-
gy lab, TEI of Crete. Amongst the 64 isolates,
26 isolates obtained from several hosts were
selected and their taxonomy was confirmed
based on their phenotypic, biochemical and
physiological characteristics, as well as their
pathogenicity on different hosts. These re-
sults were confirmed by molecular popu-
lation analyses, where the 18 isolates were
tested by rep-PCR fingerprinting (BOX- and
ERIC-PCR) as well as by Multilocus Sequence
Typing (MLST), utilizing the partial sequenc-
es of the genes
gyrB
,
rpoB
and
rpoD
. In con-
clusion, the biochemical tests and pathoge-
nicity profiling did not reveal any variability
among the isolated strains studied. How-
ever, the molecular fingerprinting patterns
and housekeeping gene sequences clear-
ly demonstrated a significant genomic vari-
ability among the 18 isolates tested.
Characterization of isolates of
Pseudomonas corrugata
and
P.
mediterranea
, causal agents of «pith necrosis» disease of tomato on Crete
M.G. P
ENTARI
, E.E. M
PALANTINAKI
, P.F. S
ARRIS
*, E.A. T
RANTAS
, F.N. V
ERVERIDIS
and D.E.
G
OUMAS
Technological Educational Institute of Crete, School of Agricultural Technology,
Department of Plant Sciences, P.O.Box 1939, 71004 Heraklion, Greece. *Present
Address: The Sainsbury Laboratory, John Innes Centre, Norwich Research Park,
Norwich NR4 7UH, UK
Pseudomonas corrugate
is a plant pathogen
that causes pith necrosis in tomato. Infect-
ed plants were identified by a general chlo-
rotic appearance, a gradual withering and
pith necrosis. Recent findings proposed that
Pseudomonas mediterranea
, which is isolat-
ed frequently from cultivated tomato fields
of countries in the Mediterranean basin, is
a related bacterium acting as a new patho-
genic agent causing pith necrosis. This
work reports the characterization of bacte-
rial isolates from pith necrosis of diseased
tomato and pepper plants on the island
of Crete, obtained within the period 1991-
2009. Amongst the 72 isolates deposited in
the collection of the Bacteriology Lab, TEI of
Crete, 36 were chosen based on phenotyp-
ic characters such as the absence of fluores-
cence and a positive oxidase reaction, the
ability to elicit the typical hypersensitive re-
action on tobacco plants and their patho-
genicity on tomato plants. Among these
36 isolates, which were analyzed by classi-
cal bacteriological tests, 28 were classified
as
P. mediterranea
and the remaining 8 as
P. corrugata
, including the reference strains
CFBP5447T and NCPPB2445 respectively. A
similar identification was also observed us-
ing the antiserum anti-PC14 for
P. corrugata
in immunofluorescence tests. These results
were further confirmed by molecular anal-
ysis using a) the species specific PCR prim-
er pairs PC1 and PC5, for the identification
of
P. mediterranea
and
P. corrugata
respec-
tively, b) by rep-PCR (BOX and ERIC) finger-
printing, and c) by Multilocus Sequence Typ-
ing (MLST) utilizing the partial sequences
of the genes
gyrB
,
rpoB
and
rpoD
. Phyloge-
netic analysis of the isolated strains did not
reveal significant genetic variability among
them. This is the first report of
Pseudomo-
nas mediterranea
as a pathogen of pith ne-
crosis disease of tomato and pepper plants
in Greece.
Comparative genomics of multiple strains of
Pseudomonas cannabina
pv.
alisalensis
, a potential model pathogen of both monocots and dicots
