Table_1_Diversity, distribution, and functional potentials of magroviruses from marine and brackish waters.XLSX

Marine group II (MGII) archaea (Ca. Poseidoniales) are among the most abundant microbes in global oceanic surface waters and play an important role in driving marine biogeochemical cycles. Magroviruses – the viruses of MGII archaea have been recently found to occur ubiquitously in surface ocean. However, their diversity, distribution, and potential ecological functions in coastal zones especially brackish waters are unknown. Here we obtained 234 non-redundant magroviral genomes from brackish surface waters by using homology searches for viral signature proteins highlighting the uncovered vast diversity of this novel viral group. Phylogenetic analysis based on these brackish magroviruses along with previously reported marine ones identified six taxonomic groups with close evolutionary connection to both haloviruses and the viruses of Marine Group I archaea. Magroviruses were present abundantly both in brackish and open ocean samples with some showing habitat specification and others having broad spectrums of distribution between different habitats. Genome annotation suggests they may be involved in regulating multiple metabolic pathways of MGII archaea. Our results uncover the previously overlooked diversity and ecological potentials of a major archaeal virial group in global ocean and brackish waters and shed light on the cryptic evolutionary history of archaeal viruses.

海洋II类古菌（Marine group II archaea, MGII）隶属于候选浮游菌目（Candidatus Poseidoniales，缩写Ca. Poseidoniales），是全球海洋表层水体中丰度最高的微生物类群之一，在驱动海洋生物地球化学循环过程中发挥关键作用。马格罗病毒（Magroviruses）——即感染MGII古菌的病毒——近期被证实广泛分布于表层海洋环境中。然而，该类病毒在沿岸带尤其是半咸水水域中的多样性、分布模式与潜在生态功能仍未被探明。本研究通过针对病毒特征蛋白的同源性搜索，从半咸水表层水体中获取了234个非冗余马格罗病毒基因组，揭示了这一新型病毒类群此前未被发掘的丰富多样性。基于本次获得的半咸水马格罗病毒及已公开报道的海洋马格罗病毒开展的系统发育分析，共鉴定出6个分类群，该类病毒与嗜盐病毒（haloviruses）及海洋I类古菌病毒均存在紧密的进化关联。马格罗病毒在半咸水与开阔大洋样本中均大量存在，部分类群呈现生境特异性，另一些类群则在不同生境中具有广泛的分布范围。基因组注释结果显示，该类病毒可能参与调控MGII古菌的多条代谢通路。本研究揭示了全球海洋与半咸水水域中一类重要古菌病毒类群此前被忽视的多样性与生态潜能，并为阐明古菌病毒隐秘的进化历史提供了新的视角。