Identification and molecular characterization of a new double-stranded RNA virus infecting Chondrostereum purpureum

• Published in: Canadian journal of plant pathology 2008-12, Vol.30 (4), p.604-613
• Main Authors: Shamoun, S.F., Varga, A., Valverde, R.A., Ramsfield, T., Sumampong, G., Elliott, M., Masri, S., James, D.
• Format: Article
• Language: English
• Subjects: Alphacryptovirus; Basidiomycetes; Biological and medical sciences; Biological control and other methods; Chondrostereum purpureum; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Parasitic plants. Weeds; Partitiviridae; Phytopathology. Animal pests. Plant and forest protection; Plant viruses and viroids; Weeds
• ISSN: 0706-0661; 1715-2992
• DOI: 10.1080/07060660809507561

A new double-stranded RNA (dsRNA) virus, designated Chondrostereum purpureum cryptic virus (CPCV), belonging to the family Partitiviridae, has been identified in the basidiomycete fungus Chondrostereum purpureum. The virus does not appear to be distributed widely and was detected in only one (PFC2064) of 20 C. purpureum isolates screened. Visualization by electron microscopy revealed isometric virus particles, approximately 30 nm in diameter. Analysis of purified dsRNA revealed two distinct bands that were cloned and sequenced. Double-stranded RNA1 was 1920 base pairs (bp) in size, and dsRNA2 was 1757 bp, excluding the poly(A) tails at the 3′ terminus of each fragment. Each RNA contains a single open reading frame (ORF) with short 5′ and 3′ untranslated regions, 44 and 115 nucleotides (nt) and 90 and 227 nt, respectively. The deduced 587 amino acid (aa) protein (M r = 68.1 kDa) encoded by the dsRNA1 ORF showed homology to the RNA-dependent RNA polymerase (RdRp) of viruses belonging to the family Partitiviridae. Eight motifs associated with RdRp were identified, including the highly conserved glycine - aspartic acid - aspartic acid sequence. The dsRNA2 ORF encodes the putative coat protein subunit (480 aa, M r = 52.8 kDa). Basic local alignment search tool analysis of the nucleotide sequence of dsRNA2 revealed no matches in GenBank; however, low identity (16%-24%) was observed for the CPCV coat protein amino acid sequence compared with members of the family Partitiviridae. The dsRNA profile, amino acid sequence alignments, and phylogenetic analyses all indicate that CPCV is most closely related to members of the genus Alphacryptovirus within the family Partitiviridae. Key words: double-stranded RNA virus, phylogenetic analysis, mycoherbicide, Alphacryptovirus, Partitiviridae mycovirus. Un nouveau virus ARN double brin (dsARN), désigné virus cryptique Chondrostereum purpureum (CPCV), de la famille Partitiviridae, a été identifié dans le basidiomycète Chondrostereum purpureum. Il ne semble pas que le virus soit très répandu et il a été détecté que dans 1 isolat (PFC2064) de C. purpureum sur 20 échantillonnés. Une visualisation au microscope électronique a montré des particules isométriques de virus d'environ 30 nm de diamètre. L'analyse d'ARN double brin purifié a révélé deux bandes distinctes qui étaient clonées et séquencées. L'ARN1 double brin contenait 1920 paires de bases (pb) et le dsARN2, 1757 pb, excluant les queues polyA situées à l'extrémité 3' de c