DNMT2 is a DNA/tRNA cytosine methyltransferase that is highly conserved in structure and function in eukaryotes. In plants however, limited information is available on the function of this methyltransferase. We have previously reported that in the moss Physcomitrella patens, DNMT2 plays a crucial role in stress recovery and tRNA^Asp transcription/stability under salt stress. To further investigate the role of PpDNMT2 at genome level, in this study we have performed RNA sequencing of ppdnmt2. Transcriptome analysis reveals a number of genes and pathways to function differentially and suggests a close link between PpDNMT2 function and osmotic and ionic stress tolerance. We propose PpDNMT2 to play a pivotal role in regulating salt tolerance by affecting molecular networks involved in stress perception and signal transduction that underlie maintenance of ion homeostasis in cells. We also examined interactome of PpDNMT2 using affinity purification (AP) coupled to mass spectrometry (AP-MS). Quantitative proteomic analysis reveals several chloroplast proteins involved in light reactions and carbon assimilation and proteins involved in stress response and some not implicated in stress to co-immunoprecipitate with PpDNMT2. Comparison between transcriptome and interactome datasets has revealed novel association between PpDNMT2 activity and the antioxidant enzyme Superoxide dismutase (SOD), protein turnover mediated by the Ubiquitin-proteasome system and epigenetic gene regulation. PpDNMT2 possibly exists in complex with CuZn-SODs in vivo and the two proteins also directly interact in the yeast nucleus as observed by yeast two-hybrid assay. Taken together, the work presented in this study sheds light on diverse roles of PpDNMT2 in maintaining molecular and physiological homeostasis in P. patens. This is a first report describing transcriptome and interactome of DNMT2 in any land plant.

DNMT2DNA / tRNA胞嘧啶甲基转移酶是真核生物的结构和功能高度保守的DNA。然而，在植物中，关于该甲基转移酶的功能的信息有限。我们以前曾报道过在青苔立枯草， DNMT2在盐胁迫下，在逆境恢复和tRNA ^Asp转录/稳定性中起着至关重要的作用。进一步调查的作用PpDNMT2 在基因组水平，在这项研究中，我们进行了RNA测序 ppdnmt2。转录组分析揭示了许多基因和途径的差异性功能，并暗示了两者之间的紧密联系PpDNMT2功能以及渗透和离子应力耐受性。我们建议PpDNMT2通过影响参与维持细胞中离子稳态的应力感知和信号转导的分子网络，在调节盐耐受性中起关键作用。我们还使用偶联质谱（AP-MS）的亲和纯化（AP）检查了PpDNMT2的相互作用组。定量蛋白质组学分析揭示了一些参与光反应和碳同化的叶绿体蛋白，以及参与应激反应的蛋白，而某些不涉及与PpDNMT2免疫共沉淀的蛋白。转录组和交互组数据集之间的比较揭示了两者之间的新颖关联PpDNMT2活性和抗氧化酶超氧化物歧化酶（SOD），泛素-蛋白酶体系统介导的蛋白质更新和表观遗传基因调控。PpDNMT2可能与CuZn-SODs复合存在体内酵母双杂交检测结果表明，这两种蛋白质还直接在酵母核中相互作用。综上所述，本研究提出的工作阐明了PpDNMT2 在维持分子和生理稳态方面 彭氏杆菌。这是第一个描述DNMT2转录组和相互作用组在任何陆地植物中的报告。