Maternal Effect
Pericarp color in maize is determined by nuclear genes
of the maternal plant. Reciprocal crosses result in
phenotypic differences.
There is a difference in reciprocal crosses for pericarp
color.
F1 seed:
prpr
red pericarp: maternal genotype is prpr
The kernels of this plant have red pericarp, due
to the genotype of the maternal parent, the genotype
of the endosperm is prprpw and of the embryo is prpw.
pwpw
white pericarp: maternal genotype is pwpw
The kernels of this plant have white pericarp, due to
the genotype of the maternal parent, the genotype of
the endosperm is pwpwpr and of the embryo is prpw.
Although the genotypes of the embryo are the same for
this reciprocal cross, the kernels on each ear have
a different pericarp color due to the effect of the
maternal parent's ovary wall. The endosperm of kernels
of each ear would exhibit red pericarp, because the
pr allele is dominant to the pw allele. However, the
pericarp tissue is maternal tissue, not endosperm tissue.
The F2 of each plant will segregate 3:1 for red:white
pericarp color for each reciprocal cross. This is because
the embryo genetic constitution is the same for both
reciprocal crosses.
