Dipartimento di Chimica e Biologia, Università di Salerno, 84084, Fisciano, SA, Italy.
Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale, 15121, Alessandria, Italy.
Environ Sci Pollut Res Int. 2014 Feb;21(3):1723-1737. doi: 10.1007/s11356-013-2072-4. Epub 2013 Aug 24.
It was previously shown that arbuscular mycorrhizal fungi (AMF) exert a significant improvement of growth in a tolerant white poplar (Populus alba L.) clone (AL35) grown on Cu- and Zn-polluted soil via foliar alterations in the levels of defence/stress-related transcripts and molecules. However, nothing is known about the epigenetic changes which occur during tolerance acquisition in response to heavy metals (HMs) in the same mycorrhizal vs. non-mycorrhizal poplar plants. In order to analyse the epigenome in leaves of AL35 plants inoculated or not with AMF and grown in a greenhouse on multimetal polluted or unpolluted soil, the Methylation Sensitive Amplification Polymorphism (MSAP) approach was adopted to detect cytosine DNA methylation. Modest changes in cytosine methylation patterns were detected at first sampling (4 months from planting), whereas extensive alterations (hypomethylation) occurred at second sampling (after 6 months) in mycorrhizal plants grown in the presence of HMs. The sequencing of MSAP fragments led to the identification of genes belonging to several Gene Ontology categories. Seven MSAP fragments, selected on the basis of DNA methylation status in treated vs control AL35 leaves at the end of the experiment, were analysed for their transcript levels by means of qRT-PCR. Gene expression varied in treated samples relative to controls in response to HMs and/or AMF inoculation; in particular, transcripts of genes involved in RNA processing, cell wall and amino acid metabolism were upregulated in the presence of AMF with or without HMs.
先前的研究表明，丛枝菌根真菌（AMF）通过叶片防御/应激相关转录本和分子水平的改变，显著促进了耐 Cu 和 Zn 污染土壤中白杨（Populus alba L.）克隆（AL35）的生长。然而，对于同一丛枝菌根和非丛枝菌根白杨植物在重金属（HM）胁迫下获得耐受性时发生的表观遗传变化，我们却知之甚少。为了分析接种或未接种 AMF 的 AL35 植株叶片的表观基因组，并在温室中研究多金属污染或未污染土壤对其的影响，我们采用甲基化敏感扩增多态性（MSAP）方法检测胞嘧啶 DNA 甲基化。首先在第一次采样（种植后 4 个月）时检测到胞嘧啶甲基化模式的微小变化，而在第二次采样（6 个月后）时，在有 HM 存在的情况下，丛枝菌根植物发生了广泛的变化（去甲基化）。对 MSAP 片段进行测序，鉴定出属于几个基因本体论（GO）类别的基因。根据实验结束时处理过的和对照的 AL35 叶片中 DNA 甲基化状态，选择了 7 个 MSAP 片段，通过 qRT-PCR 分析其转录水平。与对照相比，处理过的样本中基因表达因 HM 和/或 AMF 接种而发生变化；特别是在有或没有 AMF 的情况下，参与 RNA 加工、细胞壁和氨基酸代谢的基因的转录物被上调。
