Aphid feeding induces the relaxation of epigenetic control and the associated regulation of the defense response in Arabidopsis

Environmentally induced changes in the epigenome help individuals to quickly adapt to fluctuations in the conditions of their habitats. Here we explored those changes in Arabidopsis thaliana plants subjected to multiple biotic and abiotic stresses, and identified transposable element (TE) activation in plants infested with the green peach aphid, Myzus persicae. We performed a genome-wide analysis of DNA methylation, mRNA expression, mRNA degradation and small RNAs accumulation. Our results demonstrate that aphid feeding induces loss of methylation of hundreds of loci, mainly TEs with labile chromatin characteristics. This loss of methylation has the potential to regulate gene expression and we found evidence that it is involved in the control of key plant immunity genes. Accordingly, we find that mutant plants deficient in epigenetic silencing show increased resistance to M.persicae infestation. Collectively, our results show that changes in DNA methylation play a significant role in the regulation of the plant transcriptional response and induction of defence response against aphid feeding. Overall design: Analysis of RNA, sRNA and bisulfite sequencing during aphid infestation at 72hrs in Arabidopsis thaliana rosette leaves

环境诱导的表观基因组（epigenome）变化可帮助生物体快速适应栖息环境的条件波动。本研究针对遭受多种生物与非生物胁迫的拟南芥（Arabidopsis thaliana）开展此类变化的分析，并在被绿色桃蚜（Myzus persicae）侵染的植株中鉴定到转座因子（transposable element, TE）的激活。我们对DNA甲基化、mRNA表达、mRNA降解以及小RNA（small RNAs）的积累情况进行了全基因组分析。研究结果显示，蚜虫取食会诱导数百个基因座发生甲基化丢失，其中主要为染色质特性不稳定的转座因子。此类甲基化丢失具备调控基因表达的潜力，且我们发现其参与调控关键植物免疫基因的相关证据。据此，我们观察到表观遗传沉默缺陷的突变植株对桃蚜侵染的抗性显著增强。综上，本研究结果表明，DNA甲基化变化在植物转录响应调控以及诱导抗蚜虫取食的防御反应中发挥重要作用。整体实验设计：对拟南芥莲座叶在蚜虫侵染72小时后开展RNA、小RNA及亚硫酸氢盐测序（bisulfite sequencing）分析。