Completion of the genome sequence of Oidiodendron maius splipalmivirus 1

Mycoviruses with an unprecedented genome organization, featuring the RNA-directed RNA polymerase (RdRp) palm domain coding sequence being split into two distinct genome segments, have been found recently in a few fungi and oomycetes of different lineages and have been proposed to be named “splipalmiviruses”. One of these, Oidiodendron maius splipalmivirus 1 (OmSPV1), has been detected in the ericoid mycorrhizal fungus Oidiodendron maius, and it has been proposed to be bisegmented. Here, we complete the genome sequence of this virus by describing a third RNA segment, which is 2000 nt long and whose terminal sequences are identical to those of the other two segments of OmSPV1. This segment contains a single open reading frame that codes for a protein with unknown function and has a low level of sequence identity (47%) to the putative protein encoded by the third segment of another splipalmivirus from Magnaporthe oryzae: Magnaporthe oryzae narnavirus virus 1 (MoNV1). Based on these features, we propose the RNA segment to be the third segment of the OmSPV1 genome.