EN
After a prolonged period of uncertainty about the precise role of maternal genes in initiating embryogenesis in flowering plants, considerable evidence for the involvement of maternal genes in embryo and endosperm development in Arabidopsis thaliana has accumulated in recent years. Much attention has centered on a group of mutants known as fis, which display an ability to initiate partial embryogenesis and endosperm development in the absence of double fertilization. This article presents a brief overview of our current understanding of the role of non-zygotic parental genes in the development of these products of double fertilization in A. thaliana. Evidence shows that the expression of paternal alleles of some genes is frequently delayed during embryogenesis and endosperm development, and that the silencing occurs at the transcriptional level by genomic imprinting.