Recovery
of
S
-
locus
homozygotes
through
wide
hybridization
in
L
.
peruvianum
Bernatzky,
R
.
,
Glaven,
R
.
H
.
,
and
Chawla,
B
.
Department
of
Plant
and
Soil
Sciences,
University
of
Massachusetts,
Amherst,
MA
01003
In
our
investigation
of
self
-
incompatibility
in
tomato
we
have
sought
to
determine
functional
relationships
among
well
characterized
alleles
in
two
divergent
populations
of
L
peruvianum
.
The
alleles
S
m1
and
S
m2
(previously
designated
S
7
and
S
6
,
Liang
et
al
.
1994)
are
from
LA2163
(provided
by
C
.
M
.
Rick)
and
their
cDNA
sequences
have
been
cloned
.
The
sequence
of
S
m1
is
98%
identical
to
another
cloned
allele
S
3
which
is
derived
from
a
line
obtained
from
the
State
Dept
.
of
Agriculture,
Burnley,
Victoria,
Australia
(Mau
et
al
.
1986,
Royo
et
al
.
1994)
.
S
m2
has
high
homology
to
S
4
from
the
same
population
as
S
3
,
based
on
DNA
Southern
hybridization
(unpublished)
.
DNA
restriction
fragments
generated
with
Eco
RI
allow
us
to
genotype
individuals
bearing
these
alleles
(
S
m1
,
1
.
3
and
6
.
0
kb:
S
m2
,
0
.
6
and
4
.
2
kb,
S
3
,
3
.
5
and
6
.
2
kb;
S
4
0
.
6
and
approximately
18
.
5
kb)
.
As
with
many
S
-
alleles
of
L
peruvianum,
there
is
a
conserved
Eco
Rl
site
within
the
coding
region
.
We
made
more
than
twenty
attempts
to
cross
S
m1
Sm
2
X
S
3
S
4
(and
reciprocal)
but
succeeded
in
getting
poorly
developed
fruits
filled
primarily
with
tiny
aborted
seed
.
We
obtained
only
eight
viable
seed
and
the
seedlings
did
not
appear
to
be
hybrid
but
looked
instead
like
the
female
parents
.
Since
these
materials
are
strongly
self
-
incompatible,
we
did
not
emasculate
the
flowers
prior
to
pollination
.
RFLP
analysis
revealed
that
these
plants
were
a
result
of
self
-
fertilization
.
In
addition,
we
were
able
to
recover
individuals
homozygous
for
each
of
the
alleles
.
We
suggest
that
these
illegitimate
selfs
are
a
result
of
the
mentor
effect
of
the
distantly
related
applied
pollen
(Knox
et
al
.
1987)
.
We
have
been
previously
unable
to
produce
any
selfed
seed
of
LA2163
through
standard
bud
-
pollination,
possibly
because
of
the
early
expression
of
S
-
related
proteins
in
developing
flowers
(Rivers
and
Bernatzky
1994)
.
We
have
used
these
inbred
materials
as
pollen
testers
to
determine
relationships
among
these
alleles
.
Crosses
between
the
different
populations
are
considered
to
be
incompatible
if
the
flowers
abscise
and
compatible
if
fruits
set
(even
though
the
seeds
do
not
develop
well)
.
We
conclude
that
Sm
,
and
S
3
are
functionally
different
alleles
(i
.
e
.
compatible)
but
that
S
m2
and
S
4
,
are
the
same
alleles
.
Literature
Cited
.
Knox,
R
.
B
.
et
al
.
,
1987
.
In
Giles,
K
.
L
.
and
Prakash,
J
.
(eds
.
)
Pollen:
Cytology
and
Development
.
Academic
Press,
Inc,
London
.
Liang
W
.
et
al
.
,
1994
.
Rep
.
Torn
.
Genet
.
Coop
.
44:22
-
23
.
Mau,
S
.
L
.
et
al
.
,
1986
.
Planta
169:184
-
191
.
Rivers
B
.
R
.
and
Bernatzky
R
.
,
1994
.
Sex
.
Plant
Reprod
.
7:357
-
362
