Molecular characterisation of an endornavirus infecting the phytopathogen Sclerotinia sclerotiorum

The complete sequence and genome organisation of an endornavirus from the phytopathogenic fungus Sclerotinia sclerotiorum isolate 11691 was described and the name Sclerotinia sclerotiorum endornavirus 1 (SsEV1/11691) proposed. The genome is 10,513 nucleotides (nts) long with a single open reading frame (ORF) that codes for a single polyprotein of 3459 amino acid (aa) residues. The polyprotein contains cysteine-rich region (CRR), viral methyltransferase (MTR), putative DEXDc, viral helicase (Hel), phytoreo_S7 (S7) and RNA-dependent RNA polymerase (RdRp) domains. The polyprotein and the conserved domains are phylogenetically related to endornaviruses. However, the coding strand of SsEV1/11691 does not contain a site-specific nick characteristic of most previously described endornaviruses. The elimination of SsEV1/11691 did not result in any significant changes in the host phenotype and virulence.