Maculavirus , a new genus of plant viruses
- PDF / 168,900 Bytes
- 7 Pages / 595 x 786 pts Page_size
- 82 Downloads / 188 Views
1847
Maculavirus, a new genus of plant viruses G. P. Martelli1, S. Sabanadzovic2, N. Abou Ghanem-Sabanadzovic2, and P. Saldarelli1 1
Dipartimento di Protezione delle Piante e Microbiologia Applicata, Università degli Studi and Istituto di Virologia Vegetale del CNR, Sezione di Bari, Italy 2 Istituto Agronomico Mediterraneo, Valenzano (Bari), Italy
Summary. Maculavirus is a new genus of plant viruses typified by Grapevine fleck virus (GFkV). A possible second member is Grapevine redglobe virus (GRGV). Maculaviruses are phloem-limited non-mechanically transmissible viruses with isometric particles c. 30 nm in diameter that have a rounded contour and prominent surface structure. Vectors, if any, are unknown. GFkV preparations contain two centrifugal components, T made up of empty protein shells and B, which contains 35% RNA. The coat protein (CP) has a molecular mass of 24 kDa. The genome is a single-stranded RNA that has c. 50% cytosine residues. It is 7564 nt in size, excluding the poly(A) tail and contains four putative open reading frames (ORF) that encode a 215.4 kDa polypeptide with the conserved motifs of replication-associated proteins of positive-strand RNA viruses (ORF1), the CP (ORF2), and one (GRGV) or two (GFkV) proline-rich polyproteins of 31.4 kDa (ORF3) and 15.9 kDa (ORF4), respectively, with unknown function. Replication-associated proteins and CP are phylogenetically related to those of members of the genera Tymovirus and Marafivirus. GFkV-infected grapevine cells contain vesiculated mitochondria, the possible site of RNA replication. In the natural host, GFkV particles accumulate in great quantity, sometimes in crystalline arrays in phloem cells. Introduction Fleck, a widespread disease of grapevines (Vitis spp.), is latent in European grapevine varieties (Vitis vinifera) and in most American rootstocks [15]. The disease agent is Grapevine fleck virus (GFkV), a non-mechanically transmissible phloem-limited RNAcontaining virus with isometric particles c. 30 nm in diameter that have a rounded contour and a prominent surface structure. GFkV is not assigned to any of the currently established taxonomic groups of plant viruses [5]. Recent investigations have shown that grapevines host a family of GFkV-like viruses and for two, Grapevine asteroid mosaic-associated virus (GAMaV) and Grapevine redglobe virus (GRGV), some molecular characters and the ultrastructural effects of infection are known [19].
Virology Division News
1848
Similarities in particle morphology and physico-chemical properties exist between GFkV and members of the genera Tymovirus [9] and Marafivirus [10], but wide differences at the biological, ultrastructural, and molecular level [1, 3, 6, 19, 20] suggested that GFkV might represent a new taxon. The establishment of a novel viral genus denoted Maculavirus (from “macula” Latin for fleck) having GFkV as the type species, was therefore proposed and approved by the ICTV in June 2002. GRGV is phylogenetically closely related to GFkV and has a similar genome organization [19 and unpubl
Data Loading...
