Comparative gene expression in mature egg cell, fertilized egg cell (1-1.5 hap) and fertilized zygote (2.5-3 hap)

Egg cells represent the female partner that fuses with the sperm cell during fertilization in all multi-cellular eukaryotic organisms—and, in flowering plants, is a founder of the embryo. We examined the transcriptome of Oryza sativa ssp. japonica (cv Katy) using the Affymetrix 57K rice genome GeneChip to provide an overview of genes activated in the maternal gamete, transcripts transmitted by the paternal genome, and changes in transcript up- and down-regulation during fertilization. We used microarrays to detail the global program of gene expression in the egg cell at anthesis, complementing prior data on the male germ lineage, and following gene expression during fertilization and gamete fusion. Female gametophytic cells consisting of isolated unfertilized egg cells (0 hr after pollination = 0 hap = anthesis), in vivo pollinated 1-1.5 hap fertilized egg cells, and in vivo pollinated 2.5-3 hap fertilized zygotes were compared before and soon after plasmogamy (cellular fusion) and karyogamy (nuclear fusion). keywords: tissue expressional profile, female gametophyte germline, anthesis unfertilized egg cell, fertilized egg cell, fertilized zygote