Maumus Florian, Epert Aline, Nogué Fabien, Blanc Guillaume
1] INRA, UR1164 URGI-Research Unit in Genomics-Info, INRA de Versailles-Grignon, Route de Saint-Cyr, Versailles 78026, France [2].
INRA, UMR1318 INRA-AgroParisTech, INRA de Versailles-Grignon, Route de Saint-Cyr, Versailles 78026, France.
Nat Commun. 2014 Jun 27;5:4268. doi: 10.1038/ncomms5268.
Nucleocytoplasmic large DNA viruses (NCLDVs) are eukaryotic viruses with large genomes (100 kb-2.5 Mb), which include giant Mimivirus, Megavirus and Pandoravirus. NCLDVs are known to infect animals, protists and phytoplankton but were never described as pathogens of land plants. Here, we show that the bryophyte Physcomitrella patens and the lycophyte Selaginella moellendorffii have open reading frames (ORFs) with high phylogenetic affinities to NCLDV homologues. The P. patens genes are clustered in DNA stretches (up to 13 kb) containing up to 16 NCLDV-like ORFs. Molecular evolution analysis suggests that the NCLDV-like regions were acquired by horizontal gene transfer from distinct but closely related viruses that possibly define a new family of NCLDVs. Transcriptomics and DNA methylation data indicate that the NCLDV-like regions are transcriptionally inactive and are highly cytosine methylated through a mechanism not relying on small RNAs. Altogether, our data show that members of NCLDV have infected land plants.
核质大DNA病毒（NCLDVs）是具有大基因组（100 kb - 2.5 Mb）的真核病毒，其中包括巨型拟菌病毒、巨病毒和潘多拉病毒。已知NCLDVs可感染动物、原生生物和浮游植物，但从未被描述为陆地植物的病原体。在此，我们表明苔藓植物小立碗藓和石松植物卷柏具有与NCLDV同源物具有高度系统发育亲缘关系的开放阅读框（ORF）。小立碗藓基因聚集在DNA片段（长达13 kb）中，其中包含多达16个类似NCLDV的ORF。分子进化分析表明，类似NCLDV的区域是通过水平基因转移从不同但密切相关的病毒中获得的，这些病毒可能定义了一个新的NCLDV家族。转录组学和DNA甲基化数据表明，类似NCLDV的区域转录不活跃，并且通过不依赖小RNA的机制高度胞嘧啶甲基化。总之，我们的数据表明NCLDV的成员已感染陆地植物。
