ABSTRACT
An isolate of Lettuce mosaic virus (LMV, a Potyvirus) infecting Madagascar periwinckle (Catharanthus roseus) was identified and characterized by Illumina deep sequencing. LMV-Cr has no close affinities to previously sequenced LMV isolates and represents a novel, divergent LMV clade. Inoculation experiments with other representative LMV isolates showed that they are unable to infect C. roseus, which was not known to be a host for LMV. However, three C. roseus variants of one of these isolates, LMV-AF199, could be selected and partially or completely sequenced. These variants are characterized by the accumulation of mutations affecting the C-terminal part of the cylindrical inclusion (CI) helicase and the central part of the VPg. In particular, a serine to proline mutation at amino acid 143 of the VPg was observed in all three independently selected variants and is also present in the LMV-Cr isolate, making it a prime candidate as a host-range determinant. Other mutations at VPg positions 65 and 144 could also contribute to the ability to infect C. roseus. Inoculation experiments involving a recombinant LMV expressing a permissive lettuce eukaryotic translation initiation factor 4E (eIF4E) suggest that eIF4E does not contribute to the interaction of most LMV isolates with C. roseus.
Subject(s)
Catharanthus/virology , Genome, Viral/genetics , Lactuca/virology , Plant Diseases/virology , Potyvirus/genetics , Viral Proteins/genetics , Amino Acid Sequence , Amino Acid Substitution , Base Sequence , DNA Helicases/genetics , DNA Helicases/metabolism , Eukaryotic Initiation Factor-4E/genetics , Eukaryotic Initiation Factor-4E/metabolism , Host Specificity , Molecular Sequence Data , Mutation , Phylogeny , Plant Proteins/genetics , Plant Proteins/metabolism , Potyvirus/physiology , Sequence Analysis, DNA , Viral Proteins/metabolismABSTRACT
Though Catharanthus roseus (Madagascar periwinkle) is an ornamental plant, it is famous for its medicinal value. Its alkaloids are known for anti-cancerous properties, and this plant is studied mainly for its alkaloids. Here, this plant has been studied for its viral diseases. Complete DNA sequences of two begomoviruses infecting C. roseus originating from Pakistan were determined. The sequence of one begomovirus (clone KN4) shows the highest level of nucleotide sequence identity (86.5 %) to an unpublished virus, chili leaf curl India virus (ChiLCIV), and then (84.4 % identity) to papaya leaf curl virus (PaLCV), and thus represents a new species, for which the name "Catharanthus yellow mosaic virus" (CYMV) is proposed. The sequence of another begomovirus (clone KN6) shows the highest level of sequence identity (95.9 % to 99 %) to a newly reported virus from India, papaya leaf crumple virus (PaLCrV). Sequence analysis shows that KN4 and KN6 are recombinants of Pedilanthus leaf curl virus (PedLCV) and croton yellow vein mosaic virus (CrYVMV).
