Since developmental progression of the fertilization products occurs within female tissues of both gametophytic and sporophytic origin, the extent of maternal contributions to embryo and endosperm growth and development has been a research subject of intense interest. The two male gametes are contained inside the male gametophyte or pollen grain. The two female gametes are harbored within the female gametophyte or embryo sac.

During double fertilization, the male gametes (two haploid sperm cells) unite with the female gametes (the haploid egg cell and the diploid central cell) to form the embryo and endosperm, respectively. The gametes are formed by the haploid gametophytes, which develop inside the diploid sporophytic reproductive organs of the flowers. The embryo and the endosperm of sexually reproducing flowering plants are derived from male and female gametes and thus carry genomes of different parental origin. Collectively, our results reveal a reproductive function of plant Arm proteins in promoting early seed growth, which is achieved through a distinct GME of ZIX that involves mechanisms for maternal allele-specific expression that are independent of the well-established pathways. The maternal ZIX allele is required for the maternal expression of MINISEED3. The ZIX protein is localized in the cytoplasm and nucleus of cells in reproductive tissues and actively dividing root zones. This parent-of-origin–dependent expression is regulated by neither the histone and DNA methylation nor the DNA demethylation pathways known to regulate some other GME mutants. Expression studies revealed that ZIX manifests a GME through preferential maternal expression in the early embryo and endosperm. ZIX encodes an Armadillo repeat (Arm) protein highly conserved across eukaryotes. We present a detailed analysis of the GME mutant zak ixik ( zix), which displays delayed and arrested growth at the earliest stages of embryo and endosperm development. The characterization of many gametophytic maternal effect ( GME) mutants affecting seed development indicates that there are certain classes of genes with a predominant maternal contribution.

The proper balance of parental genomic contributions to the fertilized embryo and endosperm is essential for their normal growth and development.

Zix file extractor online