title: Phenotypic reversion in fas mutants of Arabidopsis thaliana by reintroduction of FAS genes: variable recovery of telomeres with major spatial rearrangements and transcriptional reprogramming of 45S rDNA genes.
abstract: Arabidopsis thaliana mutants dysfunctional in the evolutionarily conserved protein complex chromatin assembly factor-1 (CAF-1), which deposits the canonical histone H3 variant H3.1 during DNA synthesis-dependent chromatin assembly, display complex phenotypic changes including meristem and growth alterations, sensitivity to DNA-damaging agents, and reduced fertility. We reported previously that mutants in the FAS1 subunit of CAF-1 progressively lose telomere and 45S rDNA repeats. Here we show that multiple aspects of the fas phenotype are recovered immediately on expression of a reintroduced FAS1 allele, and are clearly independent of the recovery of rDNA copy-numbers and telomeres. In reverted lines, 45S rDNA genes are recovered to diverse levels with a strikingly different representation of their variants, and the typical association of nucleolar organizing region 4 with the nucleolus is perturbed. One of 45S rDNA variants (VAR1), which is silenced in wild-type (WT) plants without mutation history (Col-0 WT), dominates the expression pattern, whereas VAR2 is dominant in Col-0 WT plants. We propose an explanation for the variability of telomere and 45S rDNA repeats associated with CAF-1 function, suggesting that the differences in nuclear partitioning and expression of the rDNA variants in fas mutants and their revertants provide a useful experimental system to study genetic and epigenetic factors in gene dosage compensation.
authors.affiliation: Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic.|Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, Czech Republic.
authors.forename: Veronika
authors.initials: V
authors.lastname: Pavlištová
authors.affiliation: Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic.|Institute of Biophysics, Czech Academy of Sciences, Brno, Czech Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Dvořáčková
authors.affiliation: Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic.|Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, Czech Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Jež
authors.affiliation: Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic.|Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, Czech Republic.
authors.forename: Iva
authors.initials: I
authors.lastname: Mozgová
authors.affiliation: Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Mokroš
authors.affiliation: Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic.|Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, Czech Republic.|Institute of Biophysics, Czech Academy of Sciences, Brno, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Fajkus
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D004275:DNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D018745:Genome, Plant / Q000235:genetics; D016615:Telomere / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002843:Chromatin; D004275:DNA, Ribosomal
keywords: 
  rDNA
  ; CAF-1; chromatin assembly; genome instability; rRNA gene regulation; telomeres