Department of Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland; andThe Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom
Proc Natl Acad Sci U S A. 2014 Jun 10;111(23):8547-52. doi: 10.1073/pnas.1402275111. Epub 2014 May 27.
Examples of transgenerational transmission of environmentally induced epigenetic traits remain rare and disputed. Abiotic stress can release the transcription of epigenetically suppressed transposons and, noticeably, this activation is only transient. Therefore, it is likely that mechanisms countering the mitotic and meiotic inheritance of stress-triggered chromatin changes must exist but are undefined. To reveal these mechanisms, we screened for Arabidopsis mutants impaired in the resetting of stress-induced loss of epigenetic silencing and found that two chromatin regulators, Decrease in DNA methylation1 (DDM1) and Morpheus' Molecule1 (MOM1), act redundantly to restore prestress state and thus erase "epigenetic stress memory". In ddm1 mutants, stress hyperactivates heterochromatic transcription and transcription persists longer than in the wild type. However, this newly acquired state is not transmitted to the progeny. Strikingly, although stress-induced transcription in mom1 mutants is as rapidly silenced as in wild type, in ddm1 mom1 double mutants, transcriptional signatures of stress are able to persist and are found in the progeny of plants stressed as small seedlings. Our results reveal an important, previously unidentified function of DDM1 and MOM1 in rapid resetting of stress induced epigenetic states, and therefore also in preventing their mitotic propagation and transgenerational inheritance.
跨代传递环境诱导的表观遗传特征的例子仍然很少且存在争议。非生物胁迫可以释放表观遗传抑制转座子的转录，值得注意的是，这种激活是短暂的。因此，很可能存在对抗有丝分裂和减数分裂遗传应激引发染色质变化的机制，但尚未确定。为了揭示这些机制，我们筛选了拟南芥中受胁迫诱导的表观遗传沉默丧失重置缺陷的突变体，发现两个染色质调节因子，去甲基化酶 1（DDM1）和莫菲斯分子 1（MOM1），冗余地发挥作用以恢复应激前状态，从而消除“表观遗传应激记忆”。在 ddm1 突变体中，胁迫会过度激活异染色质转录，并且转录持续的时间比野生型更长。然而，这种新获得的状态不会传递给后代。引人注目的是，尽管 mom1 突变体中的胁迫诱导转录与野生型一样迅速沉默，但在 ddm1 mom1 双突变体中，应激的转录特征能够持续存在，并在作为幼苗受到胁迫的植物的后代中被发现。我们的研究结果揭示了 DDM1 和 MOM1 在快速重置应激诱导的表观遗传状态中的一个重要的、以前未被识别的功能，因此也防止了它们的有丝分裂增殖和跨代遗传。
