Next generation sequencing analysis of double-stranded RNAs from sweet cherry powdery mildew fungus Podosphaera prunicola

Pandey, Binod; Naidu, Rayapati A.; Grove, Gary G.

Next generation sequencing analysis of double-stranded RNAs from sweet cherry powdery mildew fungus Podosphaera prunicola

2018

Pandey, Binod | Naidu, Rayapati A. | Grove, Gary G.

Fungal viruses (mycoviruses) are frequently found in several plant pathogenic fungi. This study was aimed at examining mycoviral sequences in the fungus Podosphaera prunicola, the causal agent of powdery mildew disease in sweet cherry. Double-stranded RNA (dsRNA) preparations of fungal conidia and mycelium scraped from infected cherry leaves were subjected to next-generation sequencing (NGS). The quality filtered NGS reads were assembled de novo into contigs and subjected to BLASTn and BLASTx analyses against sequences available in public databases. The results showed the presence of mycovirus-related RNA sequences. Four of these sequences, ranging in size between 1915 and 2334 nucleotides (nt), contained a single open reading frame (ORF) encoding a protein with similarity to the RNA-dependent RNA polymerase of viruses in the family Partitiviridae. Three additional sequences, ranging in size between 1736 and 2104 nt, contained a single ORF encoding a putative protein similar to the capsid protein of viruses in the family Partitiviridae. Another sequence of 11,449 nt containing four putative ORFs showed similarity to the genome of Macrophomina phaseolina tobamo-like virus, an unclassified mycovirus in the family Virgaviridae. These analyses lead to the conclusion that the eight sequences represent genome segments of five novel mycoviruses.

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