Shinji Kawano

The genome sequence of pepper vein yellows virus (family Luteoviridae, genus Polerovirus)

The complete genome of pepper vein yellows virus (PeVYV) was sequenced using random amplification of RNA samples isolated from vector insects (Aphis gossypii) that had been given access to PeVYV-infected plants. The PeVYV genome consisted of 6244 nucleotides and had a genomic organization characteristic of members of the genus Polerovirus. PeVYV had highest amino acid sequence identities in ORF0 to ORF3 (75.9 - 91.9%) with tobacco vein distorting polerovirus, with which it was only 25.1% identical in ORF5. These sequence comparisons and previously studied biological properties indicate that PeVYV is a distinctly different virus and belongs to a new species of the genus Polerovirus.

Ageratumyellow vein virus isolated from tomato plants with leaf curl on Ishigaki Island, Okinawa, Japan

In 2005, severe leaf curling and yellowing were observed on tomato plants on Ishigaki Island. Because the symptoms were consistent with infection by a begomovirus, we used a polymerase chain reaction (PCR) with specific primers for begomovirus DNA-A and DNA satellite component (DNA-β) and detected products of the expected sizes from symptomatic tomato plant samples. DNA sequence analyses of the PCR products revealed that the symptomatic tomato plants were associated with Ageratum yellow vein virus (AYVV) infection. We confirmed AYVV transmission from the naturally infected weed host, Ageratum conyzoides, to healthy tomato plants by the insect vector Bemisia tabaci B biotype. This report is the first of AYVV occurrence in Japan.

Occurrence of chrysanthemum virescence caused by “Candidatus Phytoplasma aurantifolia” in Okinawa

In 1999, a disease of chrysanthemum [Dendranthema grandiflorum (Ramat.) Kitamura], characterized by virescence of flowers, occurred in Okinawa Prefecture. The causal agent was identified as “Candidatus Phytoplasma aurantifolia” based on 16S rDNA sequencing.