BIOLOGY, ETIOLOGY, GENETICS, AND CONTROL OF VIRUS DISEASES OF CORN AND SOYBEAN
Location: Corn, Soybean and Wheat Quality Research Unit
Title: Molecular and Ultrastructural Properties of Maize White Line Virus
| Russo, M - UNIVERSIT^ DEGLI STUDI |
| DE Stradis, A - UNIVERSIT^ DEGLI STUDI |
| Boscia, D - UNIVERSIT^ DEGLI STUDI |
| Rubino, L - UNIVERSIT^ DEGLI STUDI |
| Abt, John |
| Martelli, G - UNIVERSIT& DEGLI STUDI |
Submitted to: Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 2008
Publication Date: July 1, 2008
Citation: Russo, M., De Stradis, A., Boscia, D., Rubino, L., Redinbaugh, M.G., Abt, J.J., Martelli, G.P. 2008. Molecular and Ultrastructural Properties of Maize White Line Virus. Journal of Plant Pathology. 90:363-369.
Interpretive Summary: Maize white line mosaic virus (MWLMV) was first reported and characterized in the 1980's. This soil borne virus causes disease, mostly on sweetcorn, in and around the Great Lakes region. While the virion structure and single-stranded positive sense RNA genome were known, there was not sufficient information available about the virus to place it into a virus genus. The virus was grouped with the "Unassigned viruses" section of the 8th Report of the International Committee on Taxonomy of Viruses. We determined the complete genome sequence of the virus. Based on the genome structure and microscopic structures induced by the virus in infected maize, MWLMV should be classified in the Tombusviridae, and that it is most closely related to a group of plant-infecting viruses called Aureusviruses. However, there is sufficient difference between sequences of Aureusvirus species and MWLMV, that the virus should likely be placed in a separate genus. Information gained in these studies will allow for development of virus-specific molecular diagnostics and a clear distinction of MWLMV from two related maize-infecting viruses.
This paper reports the complete nucleotide sequence of the genome of Maize white line mosaic virus (MWLMV) and describes the ultrastructural features of infected maize cells. The viral genome is an RNA molecule 4293 nt in size with the same structural organization of members of the Aureusvirus and Tombusvirus genera. It comprises five ORFs flanked by non-coding regions at the 5' (40 nts) and 3' (225 nts) ends which encode, in the 5'-3' direction, proteins with predicted Mr of 30,009 (pre-readthrough), 89,140 (readthrough, replication-associated proteins), 35,080 (coat protein), 24,644 (movement protein), and 15,155 (silencing suppressor). Some of ultrastructural features of MWLMV-infected cells, e.g. lobate nuclei, localization of virus particles in tonoplast evaginations bulging into the vacuoles, plentiful occurence of virions and of aggregates of virus coat protein in the cytosol, intramitochondrial patches of electron-dense material, tallied with those reported for a number of members of the family Tombusviridae. However, differences were observed with the cytopathology of the aureusvirus Johnsongrass chlorotic streak virus (JCSMV) which is the viral species more closely related to MWLMV from the molecular point of view. MWLMV was serologically unrelated to JCSMV, Pothos latent virus (PoLV), the type species of the Aureusvirus genus, and Maize necrotic streak virus (MNeSV), another maize pathogen with similar biological properties, belonging in the family Tombusviridae. In a phylogenetic tree constructed with whole genome sequences, MWLMV clustered with all members of the genus Aureusvirus. Thus, properties and phylogenetic relationships place MWLMV in the genus Aureusvirus. However, molecular differences with all sequenced species of this genus, the lack of serological relationship with PoLV and JCSMV, and the different cytopathology elicited in infected tissues, suggest that MWLMV be regarded as a separate species. IMPACT STATEMENT: This information will be used for development of rapid, virus-specific diagnostics and management strategies for MWLMV. This virus may provide a useful alternative platform for developing virus-based gene silencing vectors for maize and other cereals.