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THE INHERHANCE OF WHITE SHEATH 2N MAIL?
THESIS FOR DEGREE OF M. S.

' FRANK H. CLARK

‘ 1926 ‘
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rm: INHERITANOI or 1mm: ssu'ra IN nnzl.

THE INHERITANCI OF WHITE SHEATH IN HAIZI
Thesis

Heepectively submitted in partial
fulfillment for the degree of Master of Science
at
Hichigan State College of Agriculture

and Applied Science

7 .

1

Frank H. Clark
'6
M .5. -

1936

Acknowledgments

The writer is grateful to Professor E. 3. Down and
Mr. H. M. Brown for guidance thruout this problem. Thanks
are due to Mr. B. B. Robinson for suggesting this problem
and to Mr. C. G. Kulkarni for constructive criticisms.
Appreciation is also due to Professor J. F. Cox,
Professor 8. E. Down, and Mr. H. M. Brown for a final
review of this problem. This thesis was begun under the
guidance of Professor F. A. Spragg, and the author

wishes to dedicate this work to his memory.

94851 -

 

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II.
III.
IV.
V.
VI.
VII.
VIII.

IX.

X.

XI.

TABLE OF CONTENTS

STATEMENT OF THE PROBLEM.
PREVIOUS INVESTIGATIONS.
SOURCE OF MATERIAL.
DESCRIPTION OF MATERIAL.
FIELD METHODS.
GREENHOUSE METHODS.
FACTORIAL COMPOSITION OF WHITE BREATH.
GENETIC RELATIONSHIP OF THIS WHITE SENATE TO
KEMPTON'S 'HITE BREATH.
THE LEAVES OF WHITE SHIATH FLANTS.
a. Chlorophyll Analysis.
GENETIC RELATIONSHIPS OF 'HITS SENATE TO
OTHER FACTORS IN HAIZI.
(1) Shrunken tndoeperm and Ihite Sheath.
(3) R. G. and White Sheath.
(3) Ligulese Leaf and Ihite Sheath.
SUMMARY.

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1.

TH! INHERITANSI 0F IHITE BREATH IN MAIZI.
1. Statement of the Problem.

I The material in this article is the result of an
attempt to contribute some more facts concerning the
behavior of white sheath in maize. The different phases
of the problem which were worked on are as follows:

1. Genetic constitution of the white sheath material.

3. Genetic relationship of this white sheath to Kemp-

ton's white sheath.

3. Genetic relationship of white sheath to other

genetic factors of maize.
It. Previous Investigations.

White sheath is one of the many chlorophyll defects
which have appeared in corn from time to time. The only
literature on white sheath up until now is a short article
by Kempton of the United States Department of Agriculture
in which he briefly describes white sheath and its geneti-
cal behavior. He showed that white sheath is recessive
to normal green and seems to behave as a simple Mendelian
recessive although he was not able to obtain consistent
Mendelian ratios in the P3 generation. as also mentioned
the fact that there are different intensities of white
sheath, and that these differences are inherited. In the
F3 of a cross made by Kempton involving white sheath and
lineate leaf there was an indication of relationship

Ibetween these two characters, but the papulation was too

small to prove linkage. -Kempton in recent correspondence

 

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intimates that white sheath is due to more than one
genetical factor.
III. Source of Material.

The white sheath material used in this study
originated from the Early Duncan Variety of corn. In
1921, twelve, fourteen, sixteen, and eighteen rowed types
of selfed ears were selected from a field of Early Duncan
corn at Michigan State College. The following year, many
of these selected ears were planted in the ear—to- row
series, remnants being saved. In 1983, remnants from
three ears of the sixteen row type were combined and used
«18 the pollen strain (36400) in one of the inter-row
crossing blocks. White sheath plants were noticed in the
pollen strain but nothing was done with them. The ears
harvested from plat 36400 were used as check in the corn
variety series of 1924. Ihite sheath plants appeared agahn
that summer, and it was these which were turned over to
the writer to determine their inheritance.

IV. Description of Material.

White sheath in corn shows up in the early seedling
stage and lasts during the entire life of the plant. In a
pOpulation segregating for white sheath, a few white
sheath plants can be distinguished two weeks after planting,
but by far the most of them cannot be distinguished with
certainty until a week.later, although the length of day,
amount of sunlight, and other growing conditions affect
the time. Table 1 will give some idea of the length of

time required for white sheath to express itself.

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Table l---- The number of white sheath seedlings in three
plantings are indicated to-gether with the date of planting,
the various dates of appearance, the number of days after

planting, and the dates harvested.

 

 

 

: No.0f days : : : : : :

: after ‘ : : : : : :

: planting : :No. : :No. : :No.

: ' : Date‘:Staked:Qgte:Staked:Date:Staked
Planted: : Dec.7: :FehS: :Ipr.I:

: : : : : : :
Staked : 15 : : Feb23: S : :

: 18 : : FebSS: 12 : :

: 19 :Dec 86: 10 : : Apr.30: 18

: 30 : : : : : ' 21° 5

: 21 : ' 28: 20 : : : ' 32- 6

: 38 : : :Mar.2 8 : ' 23: 8

: 83 : '30 : 3 : ' 3: l : ' 24: a

: 24 : : : ' 4: 4 : :

: 26 : : : ' 6: 10 : h

: 37 :Jan.3 : 2 : ' 7: l : :

: 38 : ' 4 : 3 : : : :

: 39 : '5 : l : : : :
Harvested: : Jan.9: : Mar.8: :Apr27:

 

It will be noticed that the majority of the white sheath
plants in the planting of December 7 were staked on December
36 and 28. Later it was found that a few of the plants
staked on these dates did not possess a white sheath. Be-
cause of the difficulty of positively identifying white
sheath at the end of two weeks, in subsequent progenies
only those plants were staked on a given date which were
certainly known to have white sheaths.

A glance at the table will show that the progeny
planted on April 1 required a somewhat shorter period of
growth than the other two progenies. The reason for this
difference is that the plants had more sunlight because of
the longer spring days. This table indicates that the

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final classification of a prOgeny segregating for white
sheath should not be made in most cases until four weeks
after planting.

A typical white sheath plant has the following
characteristics:- The leaf sheaths are light green to
vivid white, the whiteness in the seedling stage often
extending into and including the basal half of the leaves.
Later in develOpment, the leaves become normal green
except in some strains where the whiteness extends into
the basal portion of the leaf in the form of irregular
white stripes. This striping of the leaves may appear as
vividly on a plant with light green white sheath as on one
having white sheath of the greatest intensity, but is
usually found associated with the latter type. This white-
ness of the sheath extends from the very basal portion of
the stalk to the tassel node and includes the outer husk
covering the ear.

0n the sheath of a normal green plant, anthocyanin
pigment shows as a dull dark red color, but on a white
sheath individual it is bright red. Often the contrast
between the bright red color on the base of the stalk and
the intense white color above is very striking.

V. Field Methods.

All of the white sheath plants which appeared in the

check rows in 1924 were staked with long white poles, and

were classified into three types, A, B. and 0,-- A being
the most intensely white type, while 0 was only slightly

 

 

 

 

 

 

Fig. l.- A normal plant on the left and an A type white

sheath plant on the right. The true contrast between these

two types can be appreciated only by seeing them grow side
by side in the field.

6.

 

Fig. 2-- A normal plant (left), and a B type white sheath

plant (right). As can be seen, white sheath effects all the
sheaths of the stale, including those of the ear.

7.

 

 

Fig. 3 I- From left to right, a normal plant and a 0 type

white sheath. The contrast between these types, although
slight, is plainly evident in the field.

8.

white, and B was intermediate. As can be readily imagined,
difficulty was experienced in classifying some plants. In
general, the method used was to classify the extreme types
as A and 0 types and to put the remainder in the B class.
A tag was tied to each plant, on which was written the plot
number, plant number, and type of plant. The plants were
staked and classified the second week in July, but owing to
the fact that the season was very backward, the plants were
only in the middle of the seedling stage. A reclassification
of the plants was nade at a later date, and it was found
that they had retained their original degree of whiteness.
Out of a population of approximately 10,000 plants
there were 165 white sheath plants consisting of 22 A type,
113 B type, and 30 0 type. Many of these plants were self-
pollinated and selfed ears from the different types were
obtained as follows:-- 2 of A type, 55 of B type, and 21 of
0 type. The small number of ears obtained from the A type
plants was due partly to the fact that these plants were
used exclusively for all crossing work with the exception
of half a dozen intercrosses which were made between white
sheath types. Seven A type plants were selfed but owing to
the weakness of this type, only two ears were obtained.
Seed from these crosses and self-pollinations was
planted in the field in 1925. The plots from self-
pollinated B types showed segregation in almost every
case, but difficulties of classifying the grades of white

sheath are so great that no definite ratios were obtained.

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9.

 

Fig. 4-- The contrast between these plants is very great.
The plant marked with a cross is a typical A type white
sheath and to the right of it is the F1 of a 0 x 0 cross
with greenish-white sheaths.

10.

The plots from selfed 0 type showed much greater uniformity
than those of B type, and two or three plots were evidently
homozygous or nearly so. There were only two plots of
selfed A plants, and these gave predominantly A type.

In the summer of 1925, many selfepollinations were
made in the different plots and of the various types within
the plot. Self pollinations were also made in the F1 plots
resulting from crosses involving the other factors of maize.
Many intercrosses were made between white sheath plants of
the same plot and different plots, the type of plant being
carefully'noted.

Some F1 seed from crosses with the chromosome testers
was planted in the new greenhouse during the fall and winter
of 1924-25 for the purpose of obtaining F2 grain. In spite
of the fact that the temperature often hovered around freez-
ing, due to only temporary steam connections, these plants
finally matured to the degree of producing seed. It was
necessary to harvest this seed before it was mature, but
it grew fairly well in the field in the summer of 1925.
Owing to the limited amount of seed the plots were small
and very little data were obtained from them. They did show,
however, that the expression of white sheath is not deter-
mined by a single factor. The scarcity of white sheath
plants in these small plots made them of little value for
deteréang linkage. -

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11.

By far the greater part of the linkage tests of this
problem were made in the greenhouse during the fall and
winter of 1925—26. It was necessary to obtain most of the
linkage data from F3 progenies because no double recessivee
had been available for backcroseee. A few baokcrossee had
been made however involving dominant factors. F3 segregat-
ing progenies were grown on a bench in the greenhouse. Two
weeks after planting some white sheath plants could be
distinguished, and these were staked. white sheath plants
were staked as soon as they were detected. After three and
one half weeks no more appeared, and the plants were pulled
out at the end of four weeks, and another progeny planted.
These progenies served both for a factorial study of white
sheath and for linkage determinations.

F: progenies of crosses involving kernel characters,
or plant characters which show up in the early seedling
stage, were obviously the only material from which linkage
data could be obtained in such a short time.

Some seed of Kempton's white sheath was obtained and
grown in the greenhouse and crossed with this white sheath
to determine whether or not the two types are genetically
the same.

F1 plants of intercrosses between the A, B, and 0 types
of the writer's white sheath were grown nearly to maturity
to determine if possible what causes the different gradations
of white sheath. As far as possible, F1 material resulting

from the crossing of individuals of homozygous plots was

used.

f.

 

 

18.

 

Fig. 5 - A general view of corn growing in the greenhouse
during the winter of 1926. In the immediate foreground on
the left is a young seedling progeny spaced 4' x 4'. 0n
the right, is an F2 progeny segregating for golden and
white sheath.

13.

The rest of the green-house space was devoted to F8
progenies segregating for white sheath and some character
such as golden which requires more than four weeks to

fully express itself. In 1926 all seed planted in the
greenhouse was planted directly in the soil and not first
grown in pots as was done the year before. The methods of
planting and spacing used in this study proved very satis-
factory in dealing with white sheath.

During the winter of 1925, plants used for crossing
were spaced 15' x 15', but in 1926 a distance of 12' x 12'
proved satisfactory. Progenies segregating for white sheath
and other characters which show up in the seedling stage,
such as liguless leaf, were spaced 4' X 4'. Ihen.plants of
such progenies are grown closer together, they become
spindling, and it is difficult to determine whether or not
they have white sheaths. Plants grown as close together as
this would of course become crowded if left much longer than
four weeks.

In all crossing work, both in the field and greenhouse,
the method in vogue at Michigan State College was used.
Transparent glassine sacks 3' by 6' were used to cover the
ear buds before the silks appeared. Twelve pound size,
pinch-bottom paper sacks were used to cover the tassels,
and were clipped onto the tassel about twenty-four hours

before pollinating. When performed correctly, this method

of pollination offers little chance for outside contamination

VII. Factorial Composition of lhite Sheath.

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14.

Table 2. F3 PrOgsnies segregating for White Sheath.

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Pedigree; F1 E ObservedECalcuiateé, D : p.r.:° D
: :'- : : : : : P.I
No. : : Nor.: ws:Nor. :ws : : :
37cbss4 :norma1: 528 § 27; 518 : 37: 10 E 3.84: 2.60
: : : : : : : :
531602 :normal:‘255 : 19: 257 5:1]: 2 : 2.7: .74
: : : : : : : :
5g1604 Agnormal: 68 : g;68.56:4.5: .5: 1.38: .36
: : : : : : : :
531605 :normal: 261 : 19: 263: 17: 2 : 2.73: .74
Total : : : :
1132 : 69n107 : 74:

 

 

Total Difference : 53' 5.6
' Calculated on basis of 15:1
Results obtained from F3 and backcross data show that
white sheath depends for its expression upon the presence of
two complimentary recessive factors. The composition of a
white sheath plant may then be indicated as follows:-
wsl '91 '33 '°2° There would be 8 different types of green

plants:-

2 Val Vs1 Veg ws3
1 V31 \(s 'I '3

1 3 3
3 v31 '01 V.3%2
.4 ‘w‘l "iv-3 wea 15 Green Sheath
1 '91 vol V33 V43 1 white sheath.
3
1

we1 wrs1 V93 we2

we1 "l '93 "2

The validity of the above theory is readily seen by
referring to Tables 2 and 3. The F3 progenies in (Table 2)

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15.

in each case segregated in the ratio of 15 green sheath
to 1 white sheath, and backcrosses (Table 3) gave 3 green
sheath to 1 white sheath.

The first pedigree number in Table 2 (570—384)
represents fourteen very small F3 plots segregating for
white sheath. These plots when taken separately did not
give a definite Mendelian ratio because of their very small
size, but when taken en masse, a deviation of 10 j:3.84 was
obtained on the basis of a 15:1 ratio. Such a deviation could
be expected to occur due to chance about once in thirteen
times. This deviation although fairly large is well within
the limits of probable error. The other three pedigree
numbers in Table 2 represent the progenies of single ears.
The deviations of the progenies of these ears from a 15:1
ratio are respectively 2 g; 2.7, .5 i- 1.38, and 2 i: 2.73.
The total pepulation of these F3 progenies was 1182 and the
deviation of the total from a 15:1 ratio was 5 i=5.6. Such
a deviation would occur due to chang;:;n two trials. The
above data from F3 progenies indicate therefore that white
sheath depends for its appearance upon two complimentary

recessive factors.

 

 

 

 

Table 3. Backcrosses Involving [hits Sheath.
fidigree: T; : Observe—“cf : gglcufated: D :fid __Q_
No. : :Nor.: ws : Nor.: ws : : : P.E.
534801 :normal: 301: 64 g 199 g 66:: 2 g 4.85; .41
531200 : i i g i g g E
534302 :normalg 45 i 14 :g 45 E 15 g 1 g 3.25% .44
gaze. z s ; ; ; s.

 

'Calculated on basis of 3:1

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16.

The backcross data in Table 3 strengthen the above
supposition for in backcrosses involving white sheath, we
would expect to obtain a ratio of 3 green sheath to 1 white
sheath. The backcross and resulting genotypes expected may
be represented as follows:-

BaGkCI‘OBB V81 '81 V82 '83 X '81 '31 '32:} '83

Resulting types.
%1 '31 V33 '82

W1 wsl we8 "2 3 green sheath
'81 we1 Veg we2 to
we we we we 1 white sheath

1 1 3 2

A glance at Table 3 will show that this expectation
was realized. A very close fit to a 3:1 ratio was obtained
as the deviations were only 2 k 4.85 and l i: 2.26. These
deviations could be expected to be due to change more often
than to some other factor.

Although only A type white sheath plants were involved
in these crosses, the fact that intercrosses between the
A, B, and C types of white sheath gave only white sheath
would indicate that differences between these three types are
due to additional modifying factors, and not due to differ-
ences in the elemental factorial composition. Further work
will be necessary to establish this point. We can say however
with reasonable certainty, that two complimentary factors in
the recessive condition must be present in the case of A type
white sheath.

VIII. Genetic Relationship of this White Sheath to

Kempton's White Sheath.

During the winter of 1925-26, some of the writer's

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Fig. 6 -- Kempton's white sheath on the left and the

writer's A type on the right.

it.

 

18.

 

 

Fig. 7 -- Kempton's white sheath on the left, the writer's

white sheath on the seats-ems right, and the F1 of a cross

between these two types in the center.A normal Plant

on the extreme. right.

19.

A type white sheath plants were crossed with Kempton's

white sheath. The seed from these crosses was planted in
the green-house and the resulting plants all had white
sheaths. This proves that Kempton's white sheath plants
carry the same two recessive factors which cause the white
sheath studied in this problem. There is the possibility,
of course, that Kempton's material may contain other factors
for white sheath in addition to those demonstrated by these

crossel.
II. The Leaves of White Sheath Plants.

It has already been mentioned that in some strains of
white sheath, the whiteness of the sheath extends into the
leaves. This condition usually manifests itself in the form
of white stripes which may be fine or broad, regular or ir-
regular, and which are confined mostly to the lower leaves.
The eXpression of this striping differs so much in different
plants that it is difficult to describe it. On some white
sheath plants grown in the greenhouse, the entire basal third
of the lower leaves was vivid white in appearance, but this
condition has not as yet been noted in the field. The striping
of the leaves is generally strongest on A type plants, and
is usually lacking on C type. However, an A type plant
may lack the striping while a C type plant may possess it.

A chlorophyll analysis was made of the leaves of plots
resulting from self-pollinated A, B, and 0 types and from
intercrosses between these types. The sheaths of plants even

within a single plot differed.!omewhat in degree of whiteness,
and the only value of these results is that they demonstrate

20.

 

Fig. 8-- A normal plant on the left and an A type with

striped leaves on the right.

31.

 

 

 

 

Fig. 9 -- A normal plant (left ) and a B type with

striped leaves (right). The leaf striping shows up very
plainly in this picture and is characteristic of the A and
B types of white sheath.

82.

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V
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.5.

 

Fig. 10 -- Leaf striping is rare on a C type white sheath
plant. This picture shows a normal plant (left) and a C
type with striped leaves (right).

23.

the great variability of the chlorOphyll content in
different strains of white sheath.

The leaves to be analyzed were placed in.manila
-sacks and dried in an oven at about 600 C. for three days.
_ An electric fan was used to keep the air circulating withixi
the oven. The leaves were then ground up in a power grinder
and the resulting powder passed through a 60 mesh screen.
The chlorophyll content was determined as follows:- A 5 gram
sample of the leaf powder was placed in a flask and shaken
up in 100 to 200 c. c. of 85% acetone, and allowed to stand
for several minutes. By means of a water pump the chlorophyll
solution was sucked through filter paper into a clean flask.
This process was repeated with fresh acetone solution until
the leaf powder showed by its sclorlees appearance that it
contained practically no chlorOphyll. The extracts obtained
were diluted to a volume of 500 cc. with.85% acetone, and the
percentage of chlorophyll was then determined by the aid of
a colorimster by taking one of the samples as a 100% and
comparing the others with it. As soon as homozygous strains
can be obtained, a more exact method of analysis can then be
used. In the method described above, the different leaf
pigments were not separated. Table 4 gives the results of

these analyses.

 

 

 

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34.

Table 4 -- This table shows the % of chlorophyll found in the

leaves of white sheath plots resulting from intercrosses of

different types of white sheath plants.

 

e O.
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Strains tested _gll QPPBI :4 inlggz
C X 0 check : 100 i i

A x C 74

A x C i g g 69

B x C 78

B x C i g g 38.
c x B light plants 75

C x B i g g 51

C x C light plants 3 46

C x C i 47 g :

 

In Table 4, it will be noted that the intercross C x C
was taken as the standard. ,The leaves of these plants were
normal green in appearance although a few plants in this plot
were noticeably lighter and had striped leaves. The leaves
from these striped plants were analyzed separately. It can
be seen that in all except the standard the analysis of the
upper leaves gave nearly the same values while the lower
leaves gave widely different results. These figures show that
the lower leaves of the white sheath plants are affected much
more by the striping than the upper leaves. The results of
the above table are not comparable with those of Table 5 because
the plants of the former were grown during December and

January when there is very little sunlight, and the weather

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25.

was also mostly cloudy during this period. The material of
the latter table was grown late in the winter and was exposed

to much more sunlight.

Table 5 -- This table gives the $ of chlorophyll found in the
leaves of white sheath plots resulting from selfipollinations

and intercrosses of various white sheath plants.

 

 

 

Strain No. - 1 of Chloronhyll
36400 Check 100
c 86
B x B 75
iv1 so
av1 , 61
ma“; M71 61

 

In Table 5, the check material (green lheath) in which
white sheath first appeared was taken for the standard. Be—
cause of the smallness of the plots, the upper and lower
leaves were analyzed together. This table certainly brings out
the fact that strains of white sheath may be isolated which
differ greatly in chlorOphyll.content.

As yet, a genetical analysis of this striping of the
leaves has not been made. Segregation of the striping was
noted in the field during the summer of 1925, but definite
ratios were not obtained. The fact that all gradations from
very vivid striping down to no striping at all were noticed
in single plots would indicate that the inheritance of this
character is very complex. Before much work can be done on

this phase of the problem, it will be necessary to obtain
material which is known to be homozygous. The only conclusion

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36.

that can be advanced at the present time is that white sheath
plants differ greatly in the amount of chlorophyll in their
leaves.
Relations of lhite Sheath to other Factors in Maize.
(I) Shrunken lndosperm and Ihite Sheath.
The counts made on F3 progenies resulting from crosses
between white sheath and shrunken endosperm indicate that these

two characters are not closely linked.

Table 6.-- F3 Progeny ws1 we1 wsa weasfi 88 x Isl Isl Isa leg sh sh

 

Pedigree|_farental Combinations New Combinations

 

 

 

 

 

 

No. ; we 88 : we .63 Is 88 I we sh

531604 :_ 2 V: 29 i 69 w: 2

531602 : 14 i 67 : g_;se : 5 __
531 605 i 16 i 63 i gee : 3 __
Actual 32 159 485 10
Calculated

3:15:45:l 39 147 _§40 10
Difference 3 12 -16 o

x2 - 1.79

P = .680167

In Table 6, there is a close fit between the calcu-

lated and observed ratios. The odds against this deviation
being due to chance are .6 to 1. Such odds are insignificant.

It is true that ear 531604 had a very small number of kernels,
and the results from this one ear alone would not prove any
thing, but the progenies from ears 531602 and 531605 are
fairly large and the data from these ears certainly show that
the factor for shrunken endosperm is not closely linked with

either one of the white sheath factors although it may be

 

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27.

loosely linked with one of them.

(2) Aleurone a and White Sheath.

A few of the white sheath crosses involved the factor R.
The F1,a (CCRrAAPrPrWslwsIngwsg) of these were backcroseed
withsshite sheath plants of the composition CCrrAAPrPrwslwslwsgygz .
The purple and colorless kernels resulting from these back-
crosses were planted separately and the results are shown in
Tables 7 and 8.

Table 7.--Backeross involving aleurone R and white sheath.

—_

Colored Aleurone Colorless Aleurone

 

 

{edigree No. Is ws Is ws
534201 x 531400 97 26 104 38
Calculated 3:; 92 31 107 35
Deviation 5 g 3.24 3.: 3,43

 

Table 8.-- Backcross involving aleurone R and white sheath.

 

-.

 

 

Pedigree No. Colored Aleurone Colorless Aleurone
ls ws
534202 x 531400— 46 T4
Calculated 3:1
45 15 notgplantsd
l Ir2.26

 

lith both the colored and colorless kernels, in every case

a deviation from a 3:1 ratio was obtained which would occur
more than once in every two trials by chance. Such small
deviations indicate that neither one of the factors for white
sheath is closely linked with the aleurone factor B.

Due to lack of time and space, not all of the backcross

material involving R and white sheath was planted. Since back-

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28.
crosses involving white sheath give a 3:1 ratio of normal to
white sheath, the above populations, although small, are
sufficiently large to give reliable results.

Data obtained from some F3 progenies segregating for
white sheath and golden plant color (Cg) indirectly suggest
loose linkage between white sheath and R. It must be remem-
bered that C and R are on the same chromosome, but some
distance apart. The pOpulation involved was so small that
no definite assertions can be made. Difficulty was encount-
ered in distinguishing golden plants from the double recessive
golden-white sheath plants and for this reason no table is
given for g. The expected number of non-golden white sheath
plants failed to appear. Further work will be carried on in
the field to determine whether or not white sheath is linked
with G and R.

(3) Liguless Leaf and Ihite Sheath

Table 9 shows the ratios that were obtained from F3
progenies segregating for white sheath and liguless leaf.
Table 9.-- F2 progenies segregating for liguless leaf
and white sheath.

 

 

 

 

 

 

 

Progeny No. ‘farentaltiombinatione New Combinations
gng lslg leggy wslg
531200 11 64 181 7
531202 28 99 309 6
532100 10 47 181 3
Actual 49 210 671 16
Calculated
3:15:45:1 44 222 665 15
-5 + 12 -6 SI
13 1.33

.723973

on
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(1"

L

39.

The difference between the actual and calculated
ratios is very small, and x3 is only 1.33. The odds against
this deviation being due to chance are only .4 to 1. These
figures show that white sheath and liguless leaf are not
closely linked.

Summary

1. White sheath, a chlorophyll abnormality of maize, is
shown to depend for its expression on the presence of two
complimentary recessive factors (wsl wsl '83 wag). The great
variation in the intensity of this character makes it seem
likely that additional modifying factors are involved in its
expression.

2. Crosses between the white sheath used in this
study and Kempton's white sheath prove that the latter type
also carries the two factors wsl and '32‘

3.. Chlorophyll analyses show that the leaves of
different types of white sheath.plants differ greatly in
chlorophyll content.

4.;Linkage studies show that white sheath is not
closely linked with shrunken endosperm (sh), aleurone (R),
or liguless leaf (lg).

5. The close_fit of the actual to the theoretical
ratios in Tables 2 and 3 indicate that the two recessive
factors causing white sheath (wsl and wsa) are inherited

independently of each other.

LA

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Bibliography

Coulter, N. C. 1920. Inheritance of aleurone color in maize.
BOt. GaZe , 69‘ 407-25, NO. 50

East, E. M. 1912 Inheritance of color in the aleurone cells

of maize. Amer. Nat., 46:363-65, No.546.
Emerson, R. A. 1911. The inheritance of the ligule and
auricles of corn leaves. EXpt. Sta.Record,
28: 231.
Emerson, R. A. 1918. A Fifth pair of factors, As, for
aleurone color in maize and its Relation
to the Co and Rr Pairs. New YOrk Cornell
Sta. Mem. 16:231-89. Fig. 1.
Harris, J. Arthur 1912. A simple test of the goodness of fit
of Mendelian ratios. Amer. Nat. 46:741-45.
Hutchinson, C. B. 1921. Heritable Characters in Maize.
7. Shrunken Endosperm. Jour. Heredity
12: 76-83. Bot. Abs. 10: 262. int. 1719.

Kempton,d8. 1921. Heritable Characters of Maize.
VIII. White Sheaths. Jour. Heredity
12:224-226.

Lindetrom, E. I. 1917. Linkage in maize, aleurone and
chlorophyll factors. Amer. Rat. 51:225-
37 No. 604. Expt. Sta. Res. Vol. No.

'0

$25.53.! USE (ELY

9"- 1.‘.,- '2;

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.‘3‘ L 'U 1;

’75’ F 3:35 \4'

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