27
Molecular
mapping
of
the
Am
gene
conferring
resistance
to
Alfalfa
Mosaic
Virus
(AMV)
in
tomato
1
Parrella
G
.
,
2
Moretti,
A
.
,
3
Gognalons,
P
.
,
3
Marchoux,
G
.
,
3
Gebre
-
Selassié
K
.
and
2
Caranta
C
.
1
CNR
-
CEVICOM,
70126
Bari,
Italy;
2
INRA
-
UGAFL,
Dom
.
St
.
Maurice,
BP94,
84143
Montfavet,
France,
3
INRA
-
Pathologie
Végétale,
Dom
.
St
.
Maurice,
BP94,
84143
Montfavet,
France
E
-
mail
:
Carole
.
Caranta@avignon
.
inra
.
fr
Am
is
a
dominant
gene
derived
from
Lycopersicon
hirsutum
f
.
glabratum
PI134417
conferring
resistance
to
necrotic
and
non
necrotic
isolates
of
Alfalfa
mosaic
virus
(AMV),
belonging
to
subgroup
I
and
II
(Parrella
et
al
.
,
1998;
Parrella
et
al
.
,
2000)
.
With
the
aim
to
identify
molecular
markers
linked
to
the
Am
gene,
'bulked
segregant
analysis'
(BSA)
(Michelmore
et
al
.
,
1991)
combined
with
AFLP
markers
(Vos
et
al
.
,
1995)
were
applied
to
a
set
of
120
BC1
plants
between
the
susceptible
L
.
hirsutum
accession
PI
247087
and
the
resistant
accession
PI134417
.
The
same
BC1
plants
were
evaluated
for
resistance/susceptibility
after
mechanical
inoculation
with
the
AMV
strain
Lye
-
80
.
Among
the
109
Hind
III
-
Mse
I
primer
combinations
(primers
with
three
selective
nucleotides)
screened
on
the
susceptible
and
resistant
DNA
pools,
five
were
found
to
produce
AFLP
markers
linked
at
less
than
10
cM
from
the
Am
gene
(Fig
.
1)
.
One
primer
combination
(H35/M47)
detecting
the
same
polymorphism
(fragment
with
the
same
molecular
weight)
between
the
parental
lines
of
the
L
.
hirsutum
introgression
lines
population
(Monforte
and
Tanksley
2001)
and
L
.
hirsutum
PI134417
and
PI247087
was
used
to
assign
the
Am
gene
to
a
tomato
chromosome
.
Three
introgression
lines,
carrying
a
L
.
hirsutum
fragment
belonging
to
the
chromosome
6
(IL
-
TA1559,
IL
-
TA1546
and
IL
-
TA1545)
showed
polymorphism
suggesting
that
the
Am
is
located
to
the
tomato
chromosome
6
.
In
order
to
confirm
the
map
location
of
Am
,
RFLP
analysis
with
3
tomato
probes
from
the
tomato
chromosome
6
(TG352,
TG232
and
CT21)
was
conducted
on
the
120
BC1
plants
.
The
Am
gene
was
mapped
on
the
short
arm
of
the
chromosome
6,
3
cM
distal
to
CT21
and
TG232,
in
the
cluster
of
dominant
resistant
genes
including
Mi
,
Meu
,
Cf
-
2
,
Cf
-
9
,
Ol
-
1
and
the
major
effect
QTLs
Ty
-
1
and
Bw
-
5
.
Literature
cited
:
Michelmore
R
.
W
.
,
I
.
Paran,
R
.
V
.
Kesseli,
1991
.
Proc
.
Natl
.
Acad
.
Sci
.
USA,
88:9828
-
9832
.
Monforte
A
.
J
.
and
S
.
D
.
Tanksley,
2001
.
Theor
.
Appl
.
Genet
.
,
in
press
.
Parrella
G
.
,
H
.
Laterrot,
K
.
Gebre
Selassie,
G
.
Marchoux,
1998
.
Jour
.
of
Plant
Path
.
,
80:241
-
243
.
Parrella
G
.
,
C
.
Lanave,
G
.
Marchoux,
M
.
M
.
Finetti
Sialer,
A
.
DI
Franco,
D
.
Gallitelli,
2000
.
Arch
.
of
Virol
.
,
145:2659
-
2667
.
Figure
1
on
next
page