Correia Barbara, Valledor Luis, Hancock Robert D, Jesus Cláudia, Amaral Joana, Meijón Mónica, Pinto Glória
Department of Biology and Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, Portugal.
Plant Physiology, Department of Organisms and Systems Biology, University of Oviedo, 33005 Oviedo, Spain.
Funct Plant Biol. 2016 Sep;43(9):838-850. doi: 10.1071/FP16064.
Eucalyptus globulus Labill. is widely cultivated and used by industry but its productivity is currently restricted by drought events, so research focussing on supporting programs to breed adapted germplasm is needed. In the present work we monitored severity of acute drought stress (7 and 11 days after water withholding) and relief (2h and 3 days after rewatering) by quantifying several biochemical markers of oxidative stress and DNA methylation patterns in leaves. Water withholding imposed a mild oxidative stress as estimated by redox shifts in the major antioxidant pools and increased lipid peroxidation. At the DNA level, global 5-methylcytosine distribution increased over the dehydration period especially in vascular tissue as estimated by immunolocalisation. Using methylation-sensitive RAPD analysis, which discriminates methylation changes occurring in specific DNA sequences, we found a high number of specific demethylation events also taking place. Immunolocalisation indicated a rapid reduction in global DNA methylation 2h after rehydration; however, a large number of de novo methylation events were still detected by methylation-sensitive RAPD. These events were associated with decreased lipid peroxidation and high cellular GSH pools relative to unstressed plants. Our results indicate the parallel induction of redox and complex DNA methylation changes occurring during stress imposition and relief.
蓝桉广泛种植并被工业利用，但其生产力目前受到干旱事件的限制，因此需要开展聚焦于培育适应性种质资源的支持项目的研究。在本研究中，我们通过量化叶片中氧化应激的几种生化标记和DNA甲基化模式，监测了急性干旱胁迫（停水7天和11天后）的严重程度以及缓解情况（复水2小时和3天后）。根据主要抗氧化剂库中的氧化还原变化估计，停水施加了轻度氧化应激，并增加了脂质过氧化。在DNA水平上，通过免疫定位估计，在脱水期间，尤其是在维管组织中，整体5-甲基胞嘧啶分布增加。使用区分特定DNA序列中发生的甲基化变化的甲基化敏感RAPD分析，我们发现也发生了大量特定的去甲基化事件。免疫定位表明复水2小时后整体DNA甲基化迅速减少；然而，甲基化敏感RAPD仍检测到大量从头甲基化事件。相对于未受胁迫的植物，这些事件与脂质过氧化减少和高细胞谷胱甘肽库有关。我们的结果表明，在胁迫施加和缓解过程中，氧化还原和复杂的DNA甲基化变化同时发生。
