title: Suppressive effects of mycoviral proteins encoded by Magnaporthe oryzae chrysovirus 1 strain A on conidial germination of the rice blast fungus.
abstract: Magnaporthe oryzae chrysovirus 1 strain A (MoCV1-A) is the causal agent of growth repression and attenuated virulence (hypovirulence) of the rice blast fungus, Magnaporthe oryzae. We previously revealed that heterologous expression of the MoCV1-A ORF4 protein resulted in cytological damage to the yeasts Saccharomyces cerevisiae and Cryptococcus neoformans. Since the ORF4 protein is one of the components of viral particles, we evaluated the inhibitory effects of the purified virus particle against the conidial germination of M. oryzae, and confirmed its suppressive effects. Recombinant MoCV1-A ORF4 protein produced in Pichia pastoris was also effective for suppression of conidial germination of M. oryzae. MoCV1-A ORF4 protein sequence showed significant similarity to 6 related mycoviral proteins; Botrysphaeria dothidea chrysovirus 1, two Fusarium graminearum viruses, Fusarium oxysporum f. sp. dianthi mycovirus 1, Penicillium janczewski chrysovirus and Agaricus bisporus virus 1 in the Chrysoviridae family. Multiple alignments of the ORF4-related protein sequences showed that their central regions (210-591 aa in MoCV1-A ORF4) are relatively conserved. Indeed, yeast transformants expressing the conserved central region of MoCV1-A ORF4 protein (325-575 aa) showed similar impaired growth phenotypes as those observed in yeasts expressing the full-length MoCV1-A ORF4 protein. These data suggest that the mycovirus itself and its encoded viral protein can be useful as anti-fungal proteins to control rice blast disease caused by M. oryzae and other pathogenic fungi.
authors.affiliation: Laboratories of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Syun-Ichi
authors.initials: S
authors.lastname: Urayama
authors.affiliation: Laboratories of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Kimura
authors.affiliation: Laboratories of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Katoh
authors.affiliation: Laboratories of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ohta
authors.affiliation: Laboratories of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Nobuya
authors.initials: N
authors.lastname: Onozuka
authors.affiliation: Laboratories of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Fukuhara
authors.affiliation: Laboratories of Plant Pathology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Arie
authors.affiliation: Laboratories of Plant Pathology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Teraoka
authors.affiliation: Laboratories of Plant Pathology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: Laboratories of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan. Electronic address: hmori714@cc.tuat.ac.jp.
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Moriyama
mesh_terms: D000595:Amino Acid Sequence; D001688:Biological Products; D000067148:Fungal Viruses / Q000502:physiology*; D015870:Gene Expression; D018525:Germination / Q000187:drug effects; D012275:Oryza / Q000254:growth & development* / Q000821:virology*; D000072417:Protein Domains; D012328:RNA Viruses / Q000502:physiology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D001688:Biological Products; D011994:Recombinant Proteins; D014764:Viral Proteins; C105085:viron
keywords: Anti-fungal protein; Chrysoviridae; Double-stranded RNA; Magnaporthe oryzae.; MoCV1-A; Mycovirus