In most plants and animals, the fusion between a sperm cell produced by the father and an egg cell produced by the mother results in the development of a fertilized egg and eventually the offspring. Our studies have shown that factors brought into the fertilized egg from both the father and the mother cooperate to help fertilized eggs divide asymmetrically and the embryo grow properly. More specifically, a pseudokinase (SSP) donated from the father activates the WRKY2 transcription factor from both parents. Together with the HDG11/12 transcription factor donated from the mother, WRKY2 binds to the promoter of the WOX8 gene to promote its transcription. The activation of WOX8 then determines the vertical axis (apical-basal axis) of zygotes. Therefore, we believe that with the aid of transcriptomics, a large-scale search for genes that work downstream of these paternal factors will provide a comprehensive list of active factors that control polarization and pattern formation in fertilized eggs.

Embryos of wild type and mutant lacking parental factors
The red and blue areas indicate the apical and basal daughter cells, respectively.
Ueda et al. (2017), Genes Dev, modified
The integration of parental factors in zygote for the embryo patterning

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