RFLP
Marker
Restriction
Enzyme
TG574
DraI
TG65
BstnI
TG163
EcoRV
CT50
EcoRV
CT133
NdeI
CT173
AvaII
Table
1
.
Chromosome
4
RFLP
markers
and
restriction
enzyme
yielding
L
.
esculentum
vs
.
L
.
cheesmanii
RFLPs
.
In
order
to
place
the
Epi
locus
on
the
tomato
genetic
map
pools
of
four
“normal”
and
four
“mutant”
DNA
pools
were
created
by
combining
genomic
DNA
from
5
F2
individuals
scored
as
normal
or
mutant
with
regards
to
leaf
epinasty,
respectively
.
60
RFLP
markers
spanning
the
tomato
genome
and
spaced
at
20
-
40
cM
intervals
were
selected
from
the
tomato
RFLP
map
(8)
and
hybridized
to
the
pooled
DNAs
following
digestion
with
the
appropriate
restriction
enzyme
for
RFLP
visualization
.
RFLP
markers
which
yielded
skewed
hybridization
to
the
L
.
esculentum
allele
in
the
“mutant”
pools
were
potentially
linked
to
the
Epi
locus
.
The
first
RFLP
marker
to
demonstrate
such
skewing
was
CT50
which
had
been
previously
mapped
to
chromosome
4
(8)
.
Several
additional
RFLP
markers
from
chromosome
4
(TG65,
TG574,
CT133,
TG16,
CT173;
see
table
1)
in
addition
to
CT50
were
scored
in
a
population
of
31
randomly
chosen
L
.
esculentum
(
Epi/
Epi)
X
L
.
cheesmanii
(
epi/epi
)
F2
progeny
(including
6
individuals
demonstrating
the
epinastic
leaf
phenotype)
resulting
in
placement
of
the
Epi
locus
between
CT133
and
TG16
on
tomato
chromosome
4
(Figure
1)
.
In
summary,
the
tomato
Epi
locus
maps
to
chromosome
4
while
two
candidate
cDNAs
(TCTR1
and
TCTR2)
related
to
the
Arabidopsis
CTR1
gene
map
to
chromosome
2
and
1,
respectively
.
Genetic
localization
of
the
Epi
locus
will
facilitate
candidate
gene
testing
as
additional
putative
EPI
gene
sequences
become
available
.
In
addition,
physical
mapping
of
the
Epi
region
of
chromosome
4
will
indicate
the
feasibility
of
positional
cloning
of
the
EPI
gene
.
Literature
cited:
1
.
Fujino
D,
Burger
D,
Yang
S
-
F,
and
Bradford
K
.
(1988)
Characterization
of
an
ethylene
overproducing
mutant
of
tomato
(
Lycopersicon
esculentum
Mill
.
cultivar
VFN8)
.
Plant
Physiol
.
88:774
-
779
2
.
Ursin
V
.
(1987)
Morphogenetic
and
physiological
analyses
of
two
developmental
mutants
of
tomato,
Epinastic
and
diageotropica
.
Ph
.
D
.
Dissertation,
University
of
California,
Davis
.
3
.
Ecker
JR
.
(1995)
The
ethylene
signal
transduction
pathway
in
plants
.
Science
.
268:667
-
675
.
4
.
Fujino
D,
Burger
D,
and
Bradford
K
.
(1989)
Ineffectiveness
of
ethylene
biosynthetic
and
action
inhibitors
in
phenotypically
reverting
the
Epinastic
mutant
of
tomato
(
Lycopersicon
esculentum
Mill
.
)
.
J
.
Plant
Growth
Regul
.
8:53
-
61
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