At the molecular scale, adaptive advantages during plant growth and development rely on modulation of gene expression, primarily provided by epigenetic machinery. One crucial part of this machinery is histone posttranslational modifications, which form a flexible system, driving transient changes in chromatin, and defining particular epigenetic states. Posttranslational modifications work in concert with replication-independent histone variants further adapted for transcriptional regulation and chromatin repair. However, little is known about how such complex regulatory pathways are orchestrated and interconnected in cells. In this work, we demonstrate the utility of mass spectrometry-based approaches to explore how different epigenetic layers interact in Arabidopsis mutants lacking certain histone chaperones. We show that defects in histone chaperone function (e.g., chromatin assembly factor-1 or nucleosome assembly protein 1 mutations) translate into an altered epigenetic landscape, which aids the plant in mitigating internal instability. We observe changes in both the levels and distribution of H2A.W.7, altogether with partial repurposing of H3.3 and changes in the key repressive (H3K27me1/2) or euchromatic marks (H3K36me1/2). These shifts in the epigenetic profile serve as a compensatory mechanism in response to impaired integration of the H3.1 histone in the fas1 mutants. Altogether, our findings suggest that maintaining genome stability involves a two-tiered approach. The first relies on flexible adjustments in histone marks, while the second level requires the assistance of chaperones for histone variant replacement.

• Klíčová slova
• Arabidopsis, chromatin remodeling, histone chaperone complex, histone variants, immunochemistry, mass spectrometry, post-translational modifications,
• MeSH
• Arabidopsis * genetika   metabolismus   MeSH
• epigeneze genetická * MeSH
• faktor 1 pro uspořádání chromatinu metabolismus   genetika   MeSH
• histonové chaperony * metabolismus   genetika   MeSH
• histony * metabolismus   MeSH
• mutace MeSH
• posttranslační úpravy proteinů MeSH
• proteiny huseníčku * metabolismus   genetika   MeSH
• regulace genové exprese u rostlin MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• faktor 1 pro uspořádání chromatinu MeSH
• histonové chaperony * MeSH
• histony * MeSH
• proteiny huseníčku * MeSH

Genes encoding ribosomal RNA (rDNA) are essential for cell survival and are particularly sensitive to factors leading to genomic instability. Their repetitive character makes them prone to inappropriate recombinational events arising from collision of transcriptional and replication machineries, resulting in unstable rDNA copy numbers. In this review, we summarize current knowledge on the structure and organization of rDNA, its role in sensing changes in the genome, and its linkage to aging. We also review recent findings on the main factors involved in chromatin assembly and DNA repair in the maintenance of rDNA stability in the model plants Arabidopsis thaliana and the moss Physcomitrella patens, providing a view across the plant evolutionary tree.

• Klíčová slova
• CAF-1, RAD51, RTEL1, genome stability, rDNA organization, rRNA genes, ribosome,
• MeSH
• Arabidopsis genetika   MeSH
• DNA rostlinná genetika   MeSH
• genetická transkripce MeSH
• genová dávka MeSH
• lidé MeSH
• mechy genetika   MeSH
• nestabilita genomu MeSH
• oprava DNA * MeSH
• replikace DNA MeSH
• restrukturace chromatinu MeSH
• ribozomální DNA genetika   MeSH
• stárnutí genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• DNA rostlinná MeSH
• ribozomální DNA MeSH