Genomic methylation patterns in pre-meiotic gynoecia of wild-type and RdDM mutants of Arabidopsis.

Introduction: Although DNA methylation patterns are generally considered to be faithfully inherited in Arabidopsis thaliana (Arabidopsis), there is evidence of reprogramming during both male and female gametogenesis. The gynoecium is the floral reproductive organ from which the ovules develop and generate meiotically derived cells that give rise to the female gametophyte. It is not known whether the gynoecium can condition genomic methylation in the ovule or the developing female gametophyte.

Immunolocalization to Study ARGONAUTE Proteins in Developing Ovules of the Brassicaceae.

Determining the in situ pattern of protein expression is crucial to accurately establish regulatory function and mode of action of any plant developmental program. Here, we describe two immunolocalization procedures that are consistently used to determine subcellular localization of ARGONAUTE proteins in the ovule of the Brassicaceae. The first is performed in resin-embedded semi-thin sections of developing ovules that can be observed under bright-field microscopy.

Apomixis in flowering plants: Developmental and evolutionary considerations.

Apomixis refers to a set of reproductive mechanisms that invariably rely on avoiding meiotic reduction and fertilization of the egg cell to generate clonal seeds. After having long been considered a strictly asexual oddity leading to extinction, the integration of more than 100 years of embryological, genetic, molecular, and ecological research has revealed apomixis as a widely spread component of the dynamic processes that shape flowering plant evolution. Apomixis involves several flexible and versatile developmental pathways that can be combined within the ovule to produce offspring.

Natural variation in epigenetic pathways affects the specification of female gamete precursors in Arabidopsis.

In angiosperms, the transition to the female gametophytic phase relies on the specification of premeiotic gamete precursors from sporophytic cells in the ovule. In Arabidopsis thaliana, a single diploid cell is specified as the premeiotic female gamete precursor. Here, we show that ecotypes of Arabidopsis exhibit differences in megasporogenesis leading to phenotypes reminiscent of defects in dominant mutations that epigenetically affect the specification of female gamete precursors.

CHR11, a chromatin-remodeling factor essential for nuclear proliferation during female gametogenesis in Arabidopsis thaliana.

Chromatin-remodeling factors regulate the establishment of transcriptional programs during plant development. Although 42 genes encoding members of the SWI2/SNF2 family have been identified in Arabidopsis thaliana, <10 have been assigned a precise function on the basis of a mutant phenotype, and none have been shown to play a specific role during the gametophytic phase of the plant life cycle. A.