Maculavirus, a new genus of plant viruses
- 142 Downloads
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.
KeywordsCytosine Coat Protein Plant Virus Cytosine Residue Protein Shell
Unable to display preview. Download preview PDF.