© Benaki Phytopathological Institute
Hellenic Plant Protection Journal - Special Issue
84
and mutant strains, using thin layer chroma-
tography (TLC) and high performance liquid
chromatography (HPLC), showed that most
P. expansum
mutant strains produced patu-
lin and citrinin
in vitro
at significantly high-
er concentrations than the wild-type parent
strains. Similar results were found in tests
on artificially inoculated apples. Gene se-
quence analysis of the
Sdh
B subunit of com-
plex II, revealed that single point mutations
within a highly conserved region of the iron-
sulphur protein (Ip) conferred resistance in
most cases. Mutations resulted in replace-
ment of histidine with arginine (H272R) or
tyrosine (H272Y) at position 272. The H272R
mutation had no effect on the strains’ sen-
sitivity to fluopyram, while the H272Y mu-
tation resulted in increased sensitivity to
fluopyram. However, in one strain no muta-
tions were found in the Ip gene, though the
strain showed high resistance to boscalid
(RF: 300) and medium-high resistance to flu-
opyram (RF: 10). This is the first study report-
ing
P. expansum
strains resistant to SDHIs
due to the biochemical mechanism of tar-
get-site modification, resulting from ami-
no acid substitutions in the
Sdh
B subunit of
complex II. Moreover, the data of the pres-
ent study indicate for the first time that
P.
expansum
have the genetic and biochemi-
cal potential for the appearance of SDHI-re-
sistant isolates in the field.
Molecular characterization and PCR-RFLP detection of the E198A
benzimidazole resistance mutation in field isolates of
Monilinia laxa
from
Greece
A. M
ALANDRAKIS
, A.N. M
ARKOGLOU
and B.N. Z
IOGAS
Pesticide Science Laboratory, Agricultural University of Athens, 75 Iera Odos Str., GR-
118 55 Athens, Greece
Sensitivity to benzimidazoles in isolates of
the brown rot pathogen
Monilinia laxa
col-
lected from stone fruit in central and north-
ern Greece was evaluated and the molecular
basis for resistance was investigated.
M. laxa
isolates were classified as benzimidazole
sensitive (S) or highly resistant (HR) based
on their sensitivity profiles to carbendaz-
im. Thirty seven percent of the isolates be-
longed to the HR phenotype, carried no
apparent fitness penalties and exhibited re-
sistance factor values (based on EC
50
values)
greater than 500. Highly resistant isolates
were also less sensitive to the benzimida-
zoles benomyl and thiophanate-methyl but
weremore sensitive to the
N
-phenylcarbam-
ate diethofencarb and the benzamide zox-
amide, when compared to isolates belong-
ing to the S phenotype. Fungitoxicity tests
with fungicides belonging to other chemi-
cal classes revealed no cross-resistance rela-
tionships between benzimidazoles and the
dicarboximide iprodione, the phenylpyrrole
fludioxonil, the hydroxyanilide fenhexamid,
the carboxamide boscalid, the triazole tebu-
conazole and the strobilurin-type fungicide
pyraclostrobin, indicating that a target site
modification is probably responsible for the
resistant phenotypes observed. Compari-
son of the b-tubulin gene DNA sequences
between resistant and sensitive isolates re-
vealed a point mutation resulting from the
E198A substitution of the corresponding
protein in all HR isolates tested. An Eco31I
restriction site in the b-tubulin gene, which
was destroyed in HR
M. laxa
isolates, al-
lowed the development of a PCR-RFLP diag-
nostic for the detection of the E198A resis-
tance mutation.
Penthiopyrad (Fontelis
®
20SC) a new fungicide for the control of a large number of
diseases of fruits and vegetable crops in protected and open field environments
D. P
ANORIOS
, Y. S
TAMATAS
, J.L. G
ENET
and R. M
ATYSIAK
