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 of
uncultured, as yet unclassified plant-associated viruses have been described. Even so, the plant RNA
virosphere is still underexplored. The present study continues our investigation of the RNA virus
diversity in two riverine environments and focuses on plant-associated viruses. RNA extracted from
enriched 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 virus
sequences were detected and further analysed. The data revealed the presence of acknowledged and
novel viruses related to ten families and floating genera, i.e., of Albetovirus, Alphaflexiviridae,
Aspiviridae, Bromoviridae, Endornaviridae, Partitiviridae, Potyviridae, Solemoviridae, Tombusviridae
and Virgaviridae. Whereas all virgavirus sequences belonged to the genus Tobamovirus, the vast
majority of the remaining sequences were novel and eluded from assignment to established taxa at
the species, genus and family levels. Several tombus- and endorna-like viruses make use of alternative
translation tables which suggest that unicellular green algae (Dasycladaceae), ciliates or Hexamita
diplomonades are their hosts. The identification of 27 albeto-like viruses is remarkable as the new
sequences increases available sequence data five-fold. The capsid protein sequences enhance the
sequence 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 that
combines the Astroviridae and Potyviridae families. Less...