Sequencing of plant-associated viruses and related viruses in the Havel River and Teltowkanal, Germany

Plant-infecting RNA viruses of 30 families and floating genera are prevalent in the phytobiome,soil, sediments, human faeces and various aquatic environments. In addition, a great number ofuncultured, as yet unclassified plant-associated viruses have been described. Even so, the plant RNAvirosphere is still underexplored. The present study continues our investigation of the RNA virusdiversity in two riverine environments and focuses on plant-associated viruses. RNA extracted fromenriched virus particles of 50-L water samples of the Teltow Canal and the Havel River in Berlin,Germany, was sequenced and specifically searched for plant virus sequences. Altogether 649 virussequences were detected and further analysed. The data revealed the presence of acknowledged andnovel viruses related to ten families and floating genera, i.e., of Albetovirus, Alphaflexiviridae,Aspiviridae, Bromoviridae, Endornaviridae, Partitiviridae, Potyviridae, Solemoviridae, Tombusviridaeand Virgaviridae. Whereas all virgavirus sequences belonged to the genus Tobamovirus, the vastmajority of the remaining sequences were novel and eluded from assignment to established taxa atthe species, genus and family levels. Several tombus- and endorna-like viruses make use of alternativetranslation tables which suggest that unicellular green algae (Dasycladaceae), ciliates or Hexamitadiplomonades are their hosts. The identification of 27 albeto-like viruses is remarkable as the newsequences increases available sequence data five-fold. The capsid protein sequences enhance thesequence space of the known albetoviruses and the satellite virus of maize white line mosaic virus(Aumaivirus) and reduces the gap to the CAP protein sequences of single-stranded DNA viruses.Likewise, 16 new poty-like viruses were found to line up with other poty-like viruses in a link thatcombines the Astroviridae and Potyviridae families.