Mycoviruses related to chrysovirus affect vegetative growth in the rice blast fungus Magnaporthe oryzae.
Mycoviruses causing impaired growth and abnormal pigmentation of the host were found in the rice blast fungus, Magnaporthe oryzae. Four dsRNAs, dsRNA 1 (3554 bp), dsRNA 2 (3250 bp), dsRNA 3 (307 bp) and dsRNA 4 (3043 bp), were detected in isolate S-0412-II 1a of M. oryzae. By picking up single conidia of S-0412-II 1a, cured strains of the fungus were isolated that had completely lost the mycovirus. The cured strains had normal mycelial growth and pigmentation, suggesting that this mycovirus modulates host traits. The buoyant densities of isometric virus particles (∼35 nm diameter) containing these dsRNAs in CsCl ranged from 1.37 to 1.40 g cm⁻³. The single ORF (3384 nt) of dsRNA 1 encoded a gene product highly homologous to the viral RNA-dependent RNA polymerase of members of the family Chrysoviridae. It is noteworthy that mycovirus S-0412-II 1a was detected not only in host cells but also in culture supernatant. Furthermore, abnormal aggregation of mycelia was observed after adding the mycovirus-containing culture supernatant to an uninfected strain of M. oryzae and mycoviral dsRNAs were detectable from the aggregated mycelia. This novel dsRNA mycovirus was named Magnaporthe oryzae chrysovirus 1.
Urayama
Syunichi
S
Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan.
Kato
Sachie
S
Suzuki
Yu
Y
Aoki
Nanako
N
Le
Minh Tuong
MT
Arie
Tsutomu
T
Teraoka
Tohru
T
Fukuhara
Toshiyuki
T
Moriyama
Hiromitsu
H
D002499:Centrifugation, Density Gradient; D016000:Cluster Analysis; D020082:Magnaporthe / Q000254:growth & development* / Q000821:virology*; D008969:Molecular Sequence Data; D025282:Mycelium / Q000254:growth & development / Q000821:virology; D016366:Open Reading Frames; D012275:Oryza / Q000382:microbiology*; D010802:Phylogeny; D010860:Pigments, Biological / Q000378:metabolism; D012328:RNA Viruses / Q000254:growth & development* / Q000302:isolation & purification*; D012367:RNA, Viral / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000235:genetics
D010860:Pigments, Biological; D012367:RNA, Viral; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase