”

Pebruery 11, 195: & rib, 15

I, Hevicw of previous disucussion
1, Began consideration of the chanrse at a normal D gene to give a mutable

condition -- from recessive, colorless, c¢, to full color, C,

2. Condition found in 1 of 3500 teste gametes from an dingle plant
whose consitution was:
C Sh wx Ds Ac

C Sh wx Ds ac

 

3. It was shown that mutations to C occur only in presence of Ac

lL. Without Ac, the colorless phenotyme, recessi
an a

ve, commletely stable;
when Ac added to nucleus by ap-ropriate er

rOSS, mutaticns commence,
II, The stability of the C mutant from cml:

1. The mutant areas in c/ce/c-ml kernels:

ee The germinal mutaticns: Uow formed:
c/e-ml Ac ac Crossed to c/e: Few fully colored kernels,
These come from mutations at c-ml before gamete formation,

3. Tests of the stability of the C mutants:

a) Test tyne l: Single kernel, from above cross,

Self-pollinated for transmission of C mutant and homozygous condition.
Crossed by Ac-tester to determine presence and absence of Ae
Crossed to ec /e, ds ac -- to test for Cc phenotrpe.

Crossed toe fc Ac, == to test for reaction of © presence of Ac,
snou d it be absent from the plant being te °

nesults: The C action commictely stable in the presence of Ae.
b). Test type 2 - progeny test from a sizgle germinal mutation carr ing
Kernel, .
velf-pollinated ear derived fron plant with mutant “’ : “ernels of
all tynes selected; Tested as abOVes

Results: The game as apove, Mutnat C as stable as GC fron woleh
it was derived,

III. The presence of Ds in the ceml carrying chromosome,

1. ‘riginal cross: yee sh wx ds ac female x¥gC Sh wx Ds AC male
ree Le,
YgC Sh wx Os ac
2. The aonesrance of plant from tois kernel: Streaks of ye -- Ds tre

pattern,
PS

 

 

3e Constitution of plant was:
“N
-_ *
Ye ec Sh wx ( ) Ac
ye c sh wx ds ac
Wex Wx
. This plant erossed to ye e sh /¥eesh no Ds , no Ac
5e The c to C var, kernels in Sh Wx class removed, Plants grow: from them,
the c Sh Wx non-var, kernels removed, " " a T .
it
The ¢ sh Wx a u

The green plants (Yg/ys vlants) in each of t:

the ¢ to C kerne

a), All plants coming from +

b). None of the Yg/yg plants coning from

ese sub-cultures

nels

compared,

>

showed Yg to vs var.

the colorless Sh Wx kernels

 

showed ver, for V&e
c)y This would suggest that no Ds was at svandard loecaticn in cen
parent . (Crossovers shovld be present in the e Sh ux and
¢ sh Wx classes introducing Ds, These not found,)
7. The »larts derived from the ec to C kernels crossed to ec sh wx ds ac femal
: ceml Sh WX Ac
a)ec sh wx ds ac female x os —
c sh vx ac
b), The te-es of kernels on the ears axpected annerrance
ae .
ec Sh wx Ac ce to C var,
non-crossovers en
ec Sh wz no Ac colorless Sh wx
Crossovers, Cc-ml sh Wx Ac ec to CG sh Wx
region 1
‘ c-ml sh Wx ac colorless sh Wx
/
AO .
S ™ Crossovers,
eo. rerion 2 c-ml Bh Wx Ae ec to C Sh Wx
c-ml Sh Wx ac cc oh Wx
the ¢ sh Wx chrom-some -- nn crossovers e¢ sh wx
ec Sh wx crossover reg, 1 ec Sh wx
c sh wx " ‘2 c sh wx
c). Appesrance of kornels having e=ml and Wx: (Crossovers)

 
Ww

d). No wx areas found in
e). In the varierated
be taken un later),
to © occurs,
4 Mas s s ~ te 4?
tf). This is like the tests of

found to occur in

8. Plantg that wage c-ml Sh wx

any oF tre colorless Sh or sh

kernels, the C areas are all

germinal mutaticns
ehrcricsomes 9 with these mutants,

/¢ sh wx

wx Bernels,

Wx (exceptions to

Ds activity no longer evident when mutation

to G -= no Ds activity

Ac/ ac (original plant)

also crossed to C sh bz ds ac females:

Kernels trnes:

Conclustcns?:

ee

9.

a). Ds @lose to or at the locus of

b). No Ds at the standard location

y ce). Mutations to C associated with

No crossovers between c-ml and
Ds activity without e to

Mutations to C occur only when

Can begin to consider the

Cbs

mene

Go e- that is, ceml
in originel plant.

loss of Ds activity at the © locus,

Ds observed, No kernels found with

GC mutaticns,

possibility that c-ml arose through
transposition of Ds to the C locus,

-- colorless; action of C in-ibited,

Loss of Ds from this locug --« return of G action,

IV. Attemts to

Ll, The tests: yge

sh wx ds ac female

renove Ds by crossing over -- to set a "mutation to Ct

 

Haanterossed to Ac tester

crossed to ec Ac to test for

20,000 kernels from the test

cross

g
x Yg e=ml Sh Wx ac male
ye ce sh wx ac
com

~- none snowed any C color,
V. Attempts to remove Ds from C by breakage-~fusion-bridge evycele,. this a
small test. Not many kernels analysed.

1, The cross; Re c sh wx ds ac female x c=ml Sh Wx ac male,

wt. . 5 sos : 0 By aw
2. Meiotic prophase pairing’ Oe ee
v wy tA J p.
ew WE ~
3. the crossovers -- the anaphase bridges:
aM gp let o ‘
o—__-—-9----9- - ~*o oy | awn
A n f i ah
by

¥ om Shlve

4. The transmissible gametes: x —-e—-~-. oO.

5, quod

ch WO ee ag art Ue
a 2

5. The results: Wo cases found where color apreardda Small test,
arger test probably wovld have shown this -- formaticn of a new Ac factor,

6. Conclusions: Ds mugt be very close to the C gene vossibly a component
of it,
or
“resence of Ds alters crossimg-over: Neduced here,

Whatever the explanation, the DsC situation acts as a unite

Changes in state of cml

 

1. The original state of c-ml, Appearance of kernels with:

(oon

c wx/e wx/ c-ml Wx, Ac ac ac e
@ 1 ewe

          

The sectors with altered action: ¢

 
Found few kernels with whole area like one of the described sectors,

2. Plants grown from the selected

number of mutations to C and number of spots of We Te,

cernels with altered relationships between
& i

carefully examined and pattern analysed,

a). Nange of selections:

From very much increased Srecuency of c to © rmtations

and no wx

areas to those in woich there wre only a few C specks and

many Wk areas,

3. Bach “lant derived

ve 8

from these kernels crossed to e/c/ac female rlants,

Variegated kernels on resulting ear compared with each other and with

pattern appearing on the kernel from wich plent arose,

The result:
plant arose,
¢ to © mutations were high

Plants grown from the

Constitutions: Yg

ve c¢

l.. The appearance of the plants with

This a direct test for
et
Plant variegation

| Green; seldom if any yg

streaks

Green; few ye streaks

Green; many ye streaks

ae

very
Green;/many ys streaks,
eavily streaked,

DsG unit that alters the ratio of events
omcsome brecks to those that give

is DsC locus does not annear ¢ a
event that is altered in ratio of

°
bes
5

variegated kernels in each

cml

e rise to these changed conditions arise
te
called -- changes in state of the locus,

in kernel

the nattern of variegation resembled that/from which the
This very constant for those cases where the rate of
and the rate of appearance of wx ares were less,

of tre test trnes:
centromere Ae ac

ds centromere,

regard to Yg to yg vavriegaticn?
Yrenuency of breaks at ceml,
,o. > rely on be FY b, cycles as with the kornels, Each breaks eliminates Yg

e

Do not have to

 

Kernel type

“any c to C mutations; no wx areas

“Fkh freqencg of c¢ to C mutations;
few wk areas

Lower frequency of ¢ to C mutations
higher frequeney of wx snots

Low frequency of ec to G mutations; -
high freavenecy of wx spots

S. Conclusions:
(1) Some change has occurred to the
that give c to © mutations without chr
dicent®ic formations,

(2).The total number of events at th
changed, It is the corsequence of the
frequency.

(3). The alterations of DsC that giv
suddently -- and only when Ac is presen
(lL). These chances at the locus ave
<

II, The stability of the different altered states of ceml,

1. Changes in state occur relatively fresuently if the state under
consideration gives many dicentric chromatids as the corsequence of an event
at the DSC locus.

8. They are rare if therstate under consideration gives few dicentrics

3. If the state gives no dicentrices, or exceedingly few of them, the
state is very stable, It does not change with regard to occurrence of |i!
7 * * = + ‘
breaks -- that is, dicentric chromatids, (Emphasize the dicentric aspect)
we ee ye ete eee cn Sete tote oe nm ei ae ee Oe nent en enna 2 Ee pans cae

nhs . : : °
a). this is important, it results in a "pure" mutable gene, This
quite compsrable to other known mutable menes where breaks aprarently do not

occur or are rare,

b). This state of-c-ml is comparabge in its behavior in all major
respects to the a, - Dt condition, long known in maize,
III, The stated of Ds at its standard location illuminated by the studv of
chances in state of ceml,
f1L

1. The sudden change in action of Ds at its standard locaticn -- Ds
described earlier: ~ ‘

2. Tests mde of its stability: Quite stabbe, “ad to make very rigid
selections among many kernels to obtain a state with increased frequency of
dicentric formations,

3. The increments in increase -- occurréd stepwise,

l.. The plants -- comparisons of variegation patterns when constitutions?

 

 

Ye Z% pDsg-standard location Ac Yg cami UH ac
EF 4 ds \y — yg c yo aC
Appearance of kornel Appearance of plant Anpenarance of “ernel
SOMA if
Grn Dre We . ; d A <—
wall “2 BUS pal mn abury.
Vncely Brien ch ~7 VO incur, Me wai AACS oo) Quite
| a POLY Ae LU Adie) Vo G9 nthe,
J Ou sor, mY \ 2 \ NG <= feat ty ve
h ~ ‘ fy
Jour ao Db Cr y ULby f ) de Av L— “MA eae Any & Acauh alton
S Art, fous 4 Oates
nN tye Vaglrcr . j
0 ( y fo AML, ALLELLY A oC wutaler ?
! 3.

Gry CRAWLEY
ry me to
5. Conclusions:

fl . s * . =
aj. The Ds state reflects same co dition as at ceml with s ate heving
few dicentric forming events in comparison with mutations to C,

b). The pst pattern -- reflects only those events at Ds that give rise to
dicentrics, Probably as many other changes occur as with e=ml but the
result can not be id -ntified by a phenotrnic alteration, as with ec-mnl,
Possibly some way ca:ld be Found to detect these pheotvpic changes, but not an
easy one

wom — fY
—7 acu Io eal AE
IV, the origin of stable recessives, c, from ceml
1.fhe test: c-ml/c-ml, Ac/Ac (allelic) female x c/c/ ad/ac male

2. the ear: Pew colorless, non variega:ed kernels appeared on some
CAPS,

a). “hese covld arise from changes of Ac and losses of

b). From chanses of c-ml to give a stable c.

 

3. Some of the colorless kernels selected: Most resulted Promchanges of
Ac. A few from changes of c-ml to give stable Cy, or no c to © mutations
in the tests made,

The tests: Tests for presence of Ac -- Ac tester stock
Crossed to c/e/ with Ae to test action of e=ml
trossed to c/ ¢ no Ae,

lh, The sable ce from e-ml:

a), No ce to C mutations (within tests mace) when Ac present,

b). No dicontric Fromati-ns, -- no breaks ate

ec), A new stable, recessive ec mutant. Much like tnose stabke =
mutants obtained from a4 Dt tests.

The action of Ac on ceml and Ds-standard location when both in
same kernel,
1. The crossh c-ml wx ds; Ac female x c Wx Ds ac male,
ou State of ceml State of Ds: High frecuency

igh freaueney of ¢ to C mutations of dicentric formations
No dicentrics or rare,

2. The constitution of the kernels:

ceml wx / c-pl wx fc Wx Ds; Ac Ae ac
Background of kernel: cclorless aleurone;

Wx in starch of
underlying cells,

a). Consequence of a break at Ds -- a WK area

b). Consequence of a mutation at Ceml -- a © area in the aleurone lav-r,

3. the general apnearance of the kernels
The color in the aleu i

Leurpone layer The wx spots in the underlying
cells

lh, The changes occurring somatically to Ac to produce sectors with altered
action --~ lover dose tyne or increased dosage tyne:

Lower dese sector No Ac action sectbr

a

fo

 

5. The coincident events at cami and at Ds-stsndard:

Many coincidences observed, Some without
s in maying exact intcrpretation?

What to ex-ect

What observed:
cohhcidence, Difficulti

s

a), Changes in state of Ds as consequence of this event,
b). translocations, ete, instead of a dicentric form

mation -- occur,
Then, no wx spot need be Yormed.

 

The control of Ac on the time and the cells in weich events at both
ce-ml and Ds at standard location will occur?

1, the doses of Ac -- and easily

2. lhe

seen relationship, as shown above,

resvonses of botn to the stabilized Ac,

C sh bz wx ds ac x Sh Bz Wx Ds

vhf ©

cds ac x ceml
Stabilized Ae stabilized Ac

Aw to

 
The Transpositicn of Ds fron the locus of c-ml

1. How recognized: In sectors that are C3 in the kernels

c/e/c-ml, Ac, ac ac

c
Ds to right of ¢ aa Ds to left of C eb
Twin-spots Goer

BAF, f eveles:

fae

 

2. The occasicnal aprearance of germinal mutation with Ds inn

ew position:
in crosses of c¢ female by ceml Ac male.

To right of To left of C Twin-spots
; ai i
it volpoee abe?
yale ,
sh, 2 eel?
Glog ce OL yhbay te aE od
Pues | xb

3. The tests of the vlants derived “rom these kernels:

a). Crossed to e/e ac females

b). Kernels on esr: xmkaxkessx Show that Ds is present in ¥
carrying chromsome: QOmly about 5 or 6 casos examined,
Can remember the positions of only three of them:
\) C Ds Sh for one

2) Ds C Sh for another

ot Ds very close to C for the fourth - no twin svots

Aare aowe mur muboblo,, Carcass wit ste (

as

derp in momen este oct
Puke, Xe Laed ‘ —_ (Ea spiced 4 Adu baitour fi Mawg

Wow cthe Shen.

4 wha,

4