title: A virulence-associated, 6.4-kb, double-stranded RNA from Rhizoctonia solani is phylogenetically related to plant bromoviruses and electron transport enzymes.
abstract: We have recently shown that acquisition of a 6.4-kb, double-stranded (ds) RNA (M1) by hyphal anastomosis is associated with enhanced vigor and virulence, whereas its removal by hyphal tipping correlates with diminished virulence in the plant-pathogenic basidiomycete Rhizoctonia solani. The M1 dsRNA is not encapsidated by a typical nucleocapsid, has a circular and/or concatemeric form, and is associated with the mitochondrial and cytosolic fractions. M1 possesses six open reading frames (ORFs) the longest of which (ORF 2) is located on the (+) strand, and encodes a putative polypeptide consisting of 1,747 amino acids or 199.4 kDa. This polypeptide has a significant amino acid sequence similarity, including six conserved helicase domains and an ATP/GTP binding motif, with the 1A protein of broad bean mottle virus (BBMV) and other bromoviruses. ORF 5, which is located on the (-) strand of M1 and is complementary to a region of ORF 2, codes for a putative polypeptide that has a significant amino acid sequence similarity with the cytochrome c oxidase assembly factor. This complementarity provides direct evidence suggesting that the long-standing hypothesis of viruses evolving from cellular genes may be valid.
authors.affiliation: Department of Biological Sciences, University of Maine, Orono 04469-5722, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Jian
authors.forename: D K
authors.initials: DK
authors.lastname: Lakshman
authors.forename: S M
authors.initials: SM
authors.lastname: Tavantzis
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D017795:Bromovirus / Q000235:genetics*; D017124:Conserved Sequence; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry; D007887:Fabaceae / Q000821:virology; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D010946:Plants, Medicinal; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012330:RNA, Double-Stranded / Q000737:chemistry / Q000235:genetics*; D012232:Rhizoctonia / Q000235:genetics* / Q000472:pathogenicity*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000096:biosynthesis / Q000737:chemistry; D014774:Virulence
chemical_list: D018076:DNA, Complementary; D012329:RNA, Bacterial; D012330:RNA, Double-Stranded; D014764:Viral Proteins; D003576:Electron Transport Complex IV