Incomplete penetrance in maize genotypes segregating for the polyembryony trait


To study the genetic control of polyembryony trait in maize germplasm a series of experiments were carried out.
The genetic material came from crossings among two polyembryonic populations and 16 different genotypes,
normal type maize. A total of 27 F1 were generated in 2016, and from those, there were derived 22 F2, and 20
backcrosses genotypes. The experiments were carried out in two locations in Northern Mexico. Several genotypes
in the second generation progenies share the same preceding F1. The theoretical expectations for polyembryony
(PEm, in short) proportions in F2 and backcrossing are 0.0625 and 0.25, respectively. It is instructive to state
that given the PEm recessiveness, all the F1 genotypes were normal type plants: one seedling per germinated
seed. The statistical methods applied to the experimental data were the exact Binomial test, for the segregating
proportions in F2, and the exact Fisher test to prove for independence between environments and the PEm genotypes.
There were used R procedures for calculations. Based on the results, we have concluded that 1) varying
genetic backgrounds in crossings might have an impact on the trait segregation proportions depending upon the
specific parents’ genotypes, which eventually lead to a penetrance reduction of the PEm genes expression, 2)
polyembryony frequencies of the two populations were always statistically the same, no matter the environmental
conditions where they were grown, and 3) the trait´s inheritance model was validated.


Zea mays L., polyembryony, incomplete penetrance, environment-trait independence.

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Maydica - A journal devoted to maize and allied species

ISSN: 2279-8013