Liu Junzhong, He Zuhua
State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan and Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, China.
National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
Front Plant Sci. 2020 Dec 10;11:595603. doi: 10.3389/fpls.2020.595603. eCollection 2020.
DNA methylation is a conserved epigenetic mark that plays important roles in maintaining genome stability and regulating gene expression. As sessile organisms, plants have evolved sophisticated regulatory systems to endure or respond to diverse adverse abiotic environmental challenges, i.e., abiotic stresses, such as extreme temperatures (cold and heat), drought and salinity. Plant stress responses are often accompanied by changes in chromatin modifications at diverse responsive loci, such as 5-methylcytosine (5mC) and -methyladenine (6mA) DNA methylation. Some abiotic stress responses are memorized for several hours or days through mitotic cell divisions and quickly reset to baseline levels after normal conditions are restored, which is referred to as somatic memory. In some cases, stress-induced chromatin marks are meiotically heritable and can impart the memory of stress exposure from parent plants to at least the next stress-free offspring generation through the mechanisms of transgenerational epigenetic inheritance, which may offer the descendants the potential to be adaptive for better fitness. In this review, we briefly summarize recent achievements regarding the establishment, maintenance and reset of DNA methylation, and highlight the diverse roles of DNA methylation in plant responses to abiotic stresses. Further, we discuss the potential role of DNA methylation in abiotic stress-induced somatic memory and transgenerational inheritance. Future research directions are proposed to develop stress-tolerant engineered crops to reduce the negative effects of abiotic stresses.
DNA甲基化是一种保守的表观遗传标记，在维持基因组稳定性和调控基因表达方面发挥着重要作用。作为固着生物，植物已经进化出复杂的调控系统来耐受或应对各种不利的非生物环境挑战，即非生物胁迫，如极端温度（寒冷和炎热）、干旱和盐度。植物的胁迫反应通常伴随着不同响应位点的染色质修饰变化，如5-甲基胞嘧啶（5mC）和N6-甲基腺嘌呤（6mA）DNA甲基化。一些非生物胁迫反应通过有丝分裂细胞分裂被记忆数小时或数天，并在恢复正常条件后迅速重置为基线水平，这被称为体细胞记忆。在某些情况下，胁迫诱导的染色质标记在减数分裂中是可遗传的，并且可以通过跨代表观遗传遗传机制将胁迫暴露的记忆从亲本植物传递给至少下一代无胁迫的后代，这可能使后代具有更好适应能力的潜力。在这篇综述中，我们简要总结了关于DNA甲基化建立、维持和重置的最新成果，并强调了DNA甲基化在植物对非生物胁迫反应中的多种作用。此外，我们讨论了DNA甲基化在非生物胁迫诱导的体细胞记忆和跨代遗传中的潜在作用。提出了未来的研究方向，以开发耐胁迫的工程作物，减少非生物胁迫的负面影响。
