Chromatin organization and cell fate switch respond to positional information in Arabidopsis

Abstract

Many types of plant cell retain their developmental plasticity and have the capacity to switch fate when exposed to a new source of positional information. In the root epidermis of Arabidopsis, cells differentiate in alternating files of hair cells and non-hair cells, in response to positional information and the activity of the homoeodomain transcription factor GLABRA2 (GL2) in future non-hair cells. Here we show by three-dimensional fluorescence in situ hybridization on intact root epidermal tissue that alternative states of chromatin organization around the GL2 locus are required to control position-dependent cell-type specification. When, as a result of an atypical cell division, a cell is displaced from a hair file into a non-hair file, it switches fate. We show that during this event the chromatin state around the GL2 locus is not inherited, but is reorganized in the G1 phase of the cell cycle in response to local positional information. This ability to remodel chromatin organization may provide the basis for the plasticity in plant cell fate changes.

Chromatin assembly factor 1 regulates the cell cycle but not cell fate during male gametogenesis inArabidopsis thaliana

“…Moreover, the expression of FAS1 is activated at the G1-S transition by E2F (Ramirez-Parra and Gutierrez, 2007). Whether the cell cycle and cell fate deregulation observed in fas1 and fas2 vegetative tissues (Costa and Shaw, 2006;Exner et al, 2006) originates directly from the deficit in CAF1 or results from more indirect epigenetic deregulations caused by the absence of CAF1 has remained unclear.…”

“…In parallel to the deregulation of the cell cycle, the loss of CAF1 function causes a reduction of the heterochromatic fraction (Kirik et al, 2006), releases transcriptional gene silencing from endogenous transposons (Ono et al, 2006) and alters the pattern of histone acetylation and methylation at promoters of genes encoding components and regulators of the cell cycle (Ramirez-Parra and Gutierrez, 2007). It remains unclear whether the vegetative developmental defects in fas1 and fas2 mutants (Costa and Shaw, 2006;Exner et al, 2006) are direct consequences of the loss of CAF1 on the cell cycle or result indirectly from the gradual accumulation of epigenetic defects.…”

Putative Arabidopsis Transcriptional Adaptor Protein (PROPORZ1) is required to modulate histone acetylation in response to auxin

“…In Arabidopsis, implementation of developmental programs involves translation of positional signals into morphogenetic switches via variations in chromatin architecture (39,40). Auxin functions as such a signal, providing positional information via dynamic variations in hormone distribution (41).…”

Impact of nucleosome dynamics and histone modifications on cell proliferation during Arabidopsis development

“…At this stage, genes involved in cell-fate decisions and initiation of cell differentiation are maintained in a switched off state or reprogrammed to be active again for the new cell cycle. Such a fine-tuning has been demonstrated using three-dimensional fluorescence in situ hybridization for the homeobox gene GLABRA2 (GL2) that controls cell fate in the Arabidopsis root epidermis (Costa and Shaw, 2006). Fluorescence in situ hybridization signal detected in anaphase nuclei remains during the next G1 in atrichoblasts (cells that will become non-hair cells in the differentiated root epidermis), whereas it is lost in trichoblasts (cells that will become hair cells).…”