Allexivirus transmitted by eriophyid mites in garlic plants.

Viruses in garlic plants (Allium sativum L.) have accumulated and evolved over generations, resulting in serious consequences for the garlic trade around the world. These viral epidemics are also known to be caused by aphids and eriophyid mites (Aceria tulipae) carrying Potyviruses, Carlaviruses, and Allexiviruses. However, little is known about viral epidemics in garlic plants caused by eriophyid mites. Therefore, this study investigated the infection of garlic plants with Allexiviruses by eriophyid mites. When healthy garlic plants were cocultured with eriophyid mites, the leaves of the garlic plants developed yellow mosaic strips and became distorted. In extracts from the eriophyid mites, Allexiviruses were observed using immunosorbent electron microscopy (ISEM). From an immunoblot analysis, coat proteins against an Allexivirus garlic-virus antiserum were clearly identified in purified extracts from collected viral-infected garlic plants, eriophyid mites, and garlic plants infected by eriophyid mites. A new strain of GarV-B was isolated and named GarV-B Korea isolate 1 (GarV-B1). The ORF1 and ORF2 in GarV-B1 contained a typical viral helicase, RNA-directed RNA polymerase (RdRp), and triple gene block protein (TGBp) for viral movement between cells. The newly identified GarV-B1 was phylogenetically grouped with GarV-C and GarV-X in the Allexivirus genus. All the results in this study demonstrated that eriophyid mites are a transmitter insect species for Allexiviruses.

Poinsettia latent virus is not a cryptic virus, but a natural polerovirus-sobemovirus hybrid.

The biochemical and genetic features of Poinsettia latent virus (PnLV, formerly named Poinsettia cryptic virus), which is spread worldwide in commercial cultivars of Euphorbia pulcherrima without inducing symptoms, have been determined using virus-purification, immunological techniques, electron microscopy, cloning, and sequencing. PnLV was found to be a chimeric virus with one 4652 bases, plus strand RNA showing a close relationship to poleroviruses within the first three quarters of its genome but to sobemoviruses in the last quarter. Thus, we propose to classify this virus as "polemovirus". Similarities of protein and nucleic acid sequences at the 5' and extreme 3' end of its RNA suggest a replication mode like that of poleroviruses, whereas the coat protein sequence is closely related to that of sobemoviruses. Consistent with these results, PnLV forms stable icosahedra of 34 nm in diameter. The consequences for the taxonomy of PnLV and for gardeners' practice are discussed.