Flowering is controlled by environmental conditions and developmental regulation. The complexity of this regulation is created by an intricate network of signaling pathways. Arabidopsis is an excellent model system in which to approach this complexity, because it responds to many of the

/pdf/control-of-flowering-time-interacting-pathways-as-a-basis-1dk8of0re3.pdf

Control of flowering time: Interacting pathways as a basis for diversity

https://www.cell.com/cell/pdf/S0092-8674(02)00807-3.pdf

DEMETER, a DNA Glycosylase Domain Protein, Is Required for Endosperm Gene Imprinting and Seed Viability in Arabidopsis

Stressful 'memories' of plants: evidence and possible mechanisms

Under appropriate in vivo or in vitro conditions, certain somatic plant cells have the capability to initiate embryogenic development (somatic embryogenesis). Somatic embryogenesis provides an unique experimental model to understand the molecular and cellular bases of developmental plasticity in plants. In the last few years, the application of modern experimental techniques, as well as the characterization of Arabidopsis embryogenesis mutants, have resulted in the accumulation of novel data about the acquisition of embryogenic capabilities by somatic plant cells. In this review, we summarize relevant experimental observations that can contribute to the description and definition of a transitional state of somatic cells induced to form totipotent, embryogenic cells. During this somatic-to-embryogenic transition, cells have to dedifferentiate, activate their cell division cycle and reorganize their physiology, metabolism and gene expression patterns. The roles of stress, endogenous growth regulators and chromatin remodelling in the coordinated reorganization of the cellular state are especially emphasized.

http://www.cas.miamioh.edu/~meicenrd/pdevlmnt/feheretal2003.pdf

Transition of somatic plant cells to an embryogenic state

http://fischerlab.berkeley.edu/sites/default/files/fischerlab/Gehring_2006.pdf

DEMETER DNA Glycosylase Establishes MEDEA Polycomb Gene Self-Imprinting by Allele-Specific Demethylation

A fundamental problem in biology is to understand how fertilization initiates reproductive development. Higher plant reproduction is unique because two fertilization events are required for sexual reproduction. First, a sperm must fuse with the egg to form an embryo. A second sperm must then fuse with the adjacent central cell nucleus that replicates to form an endosperm, which is the support tissue required for embryo and/or seedling development. Here, we report cloning of the Arabidopsis FERTILIZATION-INDEPENDENT ENDOSPERM (FIE) gene. The FIE protein is a homolog of the WD motif-containing Polycomb proteins from Drosophila and mammals. These proteins function as repressors of homeotic genes. A female gametophyte with a loss-of-function allele of fie undergoes replication of the central cell nucleus and initiates endosperm development without fertilization. These results suggest that the FIE Polycomb protein functions to suppress a critical aspect of early plant reproduction, namely, endosperm development, until fertilization occurs.

Daphna Michaeli

Papers

Mutations in FIE, a WD Polycomb Group Gene, Allow Endosperm Development without Fertilization