7
RESEARCH
NOTES
TGC
REPORT
No
.
31,
1981
repulsion
gave
36%
crossovers
.
The
imb
-
irr
distance
was
20
units
in
one
test
in
repulsion
and
averaged
20
units
in
three
tests
in
coupling
.
The
irr
-
y
distance
was
36
units
for
one
repulsion
and
23
units
for
five
coupling
tests
.
This
suggests
that
the
order
is
y
-
irr
-
imb
.
This
was
confirmed
by
two
F
2
populations
having
the
three
genes
in
coupling
(Table
2)
.
From
our
work
the
order
and
location
of
the
genes
is
Kerr,E
.
A
.
Linkage
studies
of
green
ripe
Green
ripe
arose
as
a
chimeral
fruit
and
never
ripe
.
(Kerr,
TGC
8:22)
.
This
would
suggest
that
the
mutant
was
dominant
but
in
greenhouse
trials
the
green
color
of
the
heterozygous
fruits
disappeared
.
Accordingly
the
gene
was
considered
to
be
recessive
and
was
designated
gr
.
However,
tests
on
the
inheritance
of
this
gene
were
inconclusive
.
Never
ripe
(Rick,
TGC
6:22
-
23)
also
appeared
as
a
chimeral
fruit
and
appeared
superficially
to
be
a
complete
dominant
.
It
was
designated
Nr
.
It
has
been
assigned
to
chromosome
9
(Kerr,
TGC
19:12)
.
Under
field
conditions,
I
have
not
been
able
to
distinguish
these
genes
reliably
.
Both
have
delayed
production
of
red
color,
the
heterozygous
fruits
are
intermediate
in
color
and
can
be
identified
under
most
conditions
.
I
have
found
both
easier
to
score
as
dominant
genes
and
have
used
the
symbol
Gr
for
green
ripe
in
my
tests
.
In
1980,
an
F
2
was
produced
between
homozygous
Nr
and
homozygous
Gr
.
Of
the
110
plants
that
produced
ripe
fruit,
10
were
normal
red,
only
3
were
scored
as
heterozygous
mutant
and
97
were
either
Nr
or
Gr
.
This
population
was
segregating
for
some
genes
with
low
viability
and
33
plants
died
before
maturity
.
Consequently,
no
conclusions
on
possible
linkage
could
be
drawn
.
However,
these
genes
are
definitely
not
alleles
.
It
is
proposed
that
the
symbol
for
green
ripe
be
changed
from
gr
to
Gr
.