Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia.
Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, Minnesota 55108.
Plant Physiol. 2017 Dec;175(4):1893-1912. doi: 10.1104/pp.17.00744. Epub 2017 Oct 6.
Improving the responsiveness, acclimation, and memory of plants to abiotic stress holds substantive potential for improving agriculture. An unresolved question is the involvement of chromatin marks in the memory of agriculturally relevant stresses. Such potential has spurred numerous investigations yielding both promising and conflicting results. Consequently, it remains unclear to what extent robust stress-induced DNA methylation variation can underpin stress memory. Using a slow-onset water deprivation treatment in Arabidopsis (), we investigated the malleability of the DNA methylome to drought stress within a generation and under repeated drought stress over five successive generations. While drought-associated epi-alleles in the methylome were detected within a generation, they did not correlate with drought-responsive gene expression. Six traits were analyzed for transgenerational stress memory, and the descendants of drought-stressed lineages showed one case of memory in the form of increased seed dormancy, and that persisted one generation removed from stress. With respect to transgenerational drought stress, there were negligible conserved differentially methylated regions in drought-exposed lineages compared with unstressed lineages. Instead, the majority of observed variation was tied to stochastic or preexisting differences in the epigenome occurring at repetitive regions of the Arabidopsis genome. Furthermore, the experience of repeated drought stress was not observed to influence transgenerational epi-allele accumulation. Our findings demonstrate that, while transgenerational memory is observed in one of six traits examined, they are not associated with causative changes in the DNA methylome, which appears relatively impervious to drought stress.
提高植物对非生物胁迫的响应能力、适应能力和记忆能力，对于改善农业具有实质性的潜力。一个悬而未决的问题是染色质标记是否参与了与农业相关的胁迫记忆。这种潜力激发了众多的研究，产生了有希望和相互矛盾的结果。因此，仍然不清楚强烈的胁迫诱导的 DNA 甲基化变化在多大程度上可以支持胁迫记忆。我们使用拟南芥中的缓慢发生的水分剥夺处理，在一代内和连续五次的干旱胁迫下，研究了干旱胁迫下甲基组的可变性。虽然在一代内检测到了甲基组中与干旱相关的表观等位基因，但它们与干旱响应基因表达没有相关性。对六个性状进行了跨代胁迫记忆分析，干旱胁迫谱系的后代表现出一种形式的记忆，即休眠种子的增加，而且在脱离胁迫一代后仍然存在。关于跨代干旱胁迫，与未受胁迫的谱系相比，暴露于干旱中的谱系中几乎没有保守的差异甲基化区域。相反，观察到的大多数变化与拟南芥基因组重复区域的随机或预先存在的表观基因组差异有关。此外，重复的干旱胁迫经历并没有被观察到影响跨代表观等位基因的积累。我们的研究结果表明，尽管在六个被检测的性状中有一个观察到了跨代记忆，但它们与 DNA 甲基组中导致胁迫记忆的变化无关，而 DNA 甲基组似乎对干旱胁迫相对不敏感。
