Heterochromatin dynamics during developmental transitions in Arabidopsis — a focus on ribosomal DNA loci
Abstract
The Arabidopsis chromosomes contain conspicuous heterochromatin domains comprising the repetitive 45S and 5S ribosomal DNA loci as well as centromeric and pericentromeric repeats that organize into chromocenters during interphase. During developmental phase transitions such as seed maturation, germination, seedling growth and flowering that require large-scale reprogramming of gene expression patterns, the organization of repetitive sequences into chromocenters dynamically changes. Here we illustrate recent studies that shed light on the heterochromatin dynamics in cotyledons, the first aerial tissues preformed in the embryo, and in true leaves. We will summarize available data for the 5S rDNA repeat loci, in particular their chromatin organization and expression dynamics during the first days of post-germination development, and discuss how the plant accommodates 5S rRNA transcription during large-scale chromatin reorganization events.
Keywords
Ribosomal DNA Heterochromatin Development Cotyledon Arabidopsis thaliana Phase transition DAPI
4′
6′-diamidino-2-phenylindole FISH
fluorescence in situ hybridization 5mC
5 methylcytosine rDNA/rRNA
ribosomal DNA/RNA RHF
relative heterochromatin fraction ROS
repressor of silencing 1 RdDM
RNA-directed DNA methylation si-RNA
small interfering RNA TFIIIA
transcription factor IIIA
6′-diamidino-2-phenylindole
FISH
fluorescence in situ hybridization
5mC
5 methylcytosine
rDNA/rRNA
ribosomal DNA/RNA
RHF
relative heterochromatin fraction
ROS
repressor of silencing 1
RdDM
RNA-directed DNA methylation
si-RNA
small interfering RNA
TFIIIA