During homologous recombination, Dbl2 protein is required for localisation of Fbh1, an F-box helicase that efficiently dismantles Rad51-DNA filaments. RNA-seq analysis of dbl2Δ transcriptome showed that the dbl2 deletion results in upregulation of more than 500 loci in Schizosaccharomyces pombe. Compared with the loci with no change in expression, the misregulated loci in dbl2Δ are closer to long terminal and long tandem repeats. Furthermore, the misregulated loci overlap with antisense transcripts, retrotransposons, meiotic genes and genes located in subtelomeric regions. A comparison of the expression profiles revealed that Dbl2 represses the same type of genes as the HIRA histone chaperone complex. Although dbl2 deletion does not alleviate centromeric or telomeric silencing, it suppresses the silencing defect at the outer centromere caused by deletion of hip1 and slm9 genes encoding subunits of the HIRA complex. Moreover, our analyses revealed that cells lacking dbl2 show a slight increase of nucleosomes at transcription start sites and increased levels of methylated histone H3 (H3K9me2) at centromeres, subtelomeres, rDNA regions and long terminal repeats. Finally, we show that other proteins involved in homologous recombination, such as Fbh1, Rad51, Mus81 and Rad54, participate in the same gene repression pathway.
- MeSH
- centromera MeSH
- histonový kód MeSH
- homologní rekombinace * MeSH
- nukleozomy metabolismus MeSH
- proteiny buněčného cyklu antagonisté a inhibitory metabolismus MeSH
- regulace genové exprese u hub * MeSH
- represorové proteiny fyziologie MeSH
- Schizosaccharomyces pombe - proteiny antagonisté a inhibitory metabolismus fyziologie MeSH
- Schizosaccharomyces genetika MeSH
- transkripční faktory antagonisté a inhibitory metabolismus MeSH
- umlčování genů * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
True day-neutral (DN) plants flower regardless of day-length and yet they flower at characteristic stages. DN Nicotiana tabacum cv. Samsun, makes about forty nodes before flowering. The question still persists whether flowering starts because leaves become physiologically able to export sufficient floral stimulus or the shoot apical meristem (SAM) acquires developmental competence to interpret its arrival. This question was addressed using tobacco expressing the Schizosaccharomyces pombe cell cycle gene, Spcdc25, as a tool. Spcdc25 expression induces early flowering and we tested a hypothesis that this phenotype arises because of premature floral competence of the SAM. Scions of vegetative Spcdc25 plants were grafted onto stocks of vegetative WT together with converse grafts and flowering onset followed (as the time since sowing and number of leaves formed till flowering). Spcdc25 plants flowered significantly earlier with fewer leaves, and, unlike WT, also formed flowers from axillary buds. Scions from vegetative Spcdc25 plants also flowered precociously when grafted to vegetative WT stocks. However, in a WT scion to Spcdc25 stock, the plants flowered at the same time as WT. SAMs from young vegetative Spcdc25 plants were elongated (increase in SAM convexity determined by tracing a circumference of SAM sections) with a pronounced meristem surface cell layers compared with WT. Presumably, Spcdc25 SAMs were competent for flowering earlier than WT and responded to florigenic signal produced even in young vegetative WT plants. Precocious reproductive competence in Spcdc25 SAMs comprised a pronounced mantle, a trait of prefloral SAMs. Hence, we propose that true DN plants export florigenic signal since early developmental stages but the SAM has to acquire competence to respond to the floral stimulus.
- MeSH
- geneticky modifikované rostliny genetika MeSH
- květy genetika fyziologie MeSH
- meristém genetika fyziologie MeSH
- proteinfosfatasy biosyntéza genetika fyziologie MeSH
- Schizosaccharomyces pombe - proteiny biosyntéza genetika fyziologie MeSH
- tabák fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
