Hayes and Garber - Cucurbit Breeding

necessary for the production
MAIZE BREEDING 187
of red aleurone. These Emerson
(1918) has called R, C, and A. In addition to these three
factors, Pr, in either the simplex or duplex condition, gives
purple aleurone. An inhibitory factor which was called / was
first discovered by East and Hayes (1911). When this is present,
the aleurone layer is colorless. Races of white corn exist which
contain some but not all of the factors necessary for the production
of aleurone color. Certain crosses between white races
give colored aleurone. With five or six factors involved, it
becomes apparent that segregation in certain cases may be in a
simple 3:1 ratio, while segregation in other crosses may give
extremely complex ratios. There are various intensities of the
purple color in different races. These have been discussed in
detail by Emerson (1918). Over waxy or floury endosperm
purple aleurone gives a dull black appearance. With a variation
in color of the endosperm from white to dark yellow there
is a corresponding variation in color of the aleurone from purple
to brownish shades. These differences in aleurone appearance
are due to the inheritance of other genetic factors for endosperm
characters beside those which govern the ability to produce
aleurone color. There are some genetic differences in aleurone
colors which are not related to the underlying endosperm
characters. Two color patterns have been mentioned by
Emerson under the names speckled and dark-capped. The
color is found on the crown of the seed and varies from a mere
speck to a large spot. Both color patterns are recessive to
normal or self-color. Aside from these color patterns which are
apparent in homozygous races, there are mottled colors which
are only obtained in the heterozygous condition. Emerson has
given quite conclusive proof that mottling is associated with the
Rr factor pair. Apparently endosperms of the constitution
RRR or RRr are self-colored while Rrr shows mottling.
Colors in Plant Organs.
PLANT CHARACTERS
There is a group of anthocyan color
characters which are expressed in one or all of the following
organs: cob, pericarp, silk, tassel, i.e., glume, and in the leaves
and stems. There are several different character expressions
of a stable nature for this group of color characters. In some
cases the color in two or more organs may be inherited as if due