Meristem-specific expression of epigenetic regulators safeguards transposon silencing in Arabidopsis
Meristem-specific expression of epigenetic regulators safeguards transposon silencing in Arabidopsis
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DOI：
10.1002/embr.201337915
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发表时间：
2014-04-01
期刊：
影响因子：
7.7
通讯作者：
Pecinka, Ales
中科院分区：
文献类型：
--
作者：
Baubec, Tuncay;Finke, Andreas;Pecinka, Ales
同视图像重复的DNA序列在植物胚胎组织中容易被激活。茎尖分生组织中的增强沉默在这里被证明可以阻止它们在胚后组织中的表达。DNA甲基化抑制剂zebularine诱导胚胎中重复序列的转录激活，但不诱导胚后，RNA依赖的DNA甲基化（RdDM）是茎顶端分生组织（SAM）中这些序列重新沉默所必需的。在植物中，转座因子（transposable elements，TE）通过转录基因沉默（transformational gene silencing，TGS）保持失活。TGS分别通过RNA指导的DNA甲基化（RdDM）和维持甲基化途径建立和延续。在这里，我们描述了一种新的RdDM功能，具体的茎尖分生组织，加强沉默的TE在早期营养生长。在分生组织中，RdDM抵消了药物诱导的对TGS维持的干扰，从而防止TE激活。两个TGS途径的同时干扰导致由体细胞组织和部分由后代遗传的重复序列的转录活性状态。这种顶端分生组织特异性机制由TGS因子水平的增加介导，并在从营养期到生殖期以及到下一代的过渡期间为正确的表观遗传提供检查点。
SynopsisimageRepetitive DNA sequences are prone to be activated in plant embryonic tissues. Reinforced silencing in the shoot apical meristem is shown here to prevent their expression in post-embryonic tissues.The DNA methylation inhibitor zebularine induces transcriptional activation of repetitive sequences in embryonic, but not post-embryonic, plant tissues.RNA-dependent DNA methylation (RdDM) is required for re-silencing of these sequences in the shoot apical meristem (SAM).Abundance of de novo and maintenance methylation factors in the SAM secure correct transmission of epigenetic states during vegetative growth.AbstractIn plants, transposable elements (TEs) are kept inactive by transcriptional gene silencing (TGS). TGS is established and perpetuated by RNA-directed DNA methylation (RdDM) and maintenance methylation pathways, respectively. Here, we describe a novel RdDM function specific for shoot apical meristems that reinforces silencing of TEs during early vegetative growth. In meristems, RdDM counteracts drug-induced interference with TGS maintenance and consequently prevents TE activation. Simultaneous disturbance of both TGS pathways leads to transcriptionally active states of repetitive sequences that are inherited by somatic tissues and partially by the progeny. This apical meristem-specific mechanism is mediated by increased levels of TGS factors and provides a checkpoint for correct epigenetic inheritance during the transition from vegetative to reproductive phase and to the next generation.