Plant viruses and viroids in Japan

Journal of General Plant Pathology - An increasing number of plant viruses and viroids have been reported from all over the world due largely to metavirogenomics approaches with technological...     

First report of <Emphasis Type="Italic">Bean common mosaic virus</Emphasis> in yam bean [<Emphasis Type="Italic">Pachyrhizus erosus</Emphasis> (L.) Urban] in Indonesia

Severe mosaic with leaf malformation and green vein banding was observed on yam bean in West and Central Java, Indonesia. Virions of the causal virus were flexuous filaments, about 700 nm in length, with a coat protein of 30 kDa. The virus was transmitted by mechanical inoculation and by aphids in a nonpersistent manner. The nucleotide sequence of the coat protein gene had the highest identity with that of Bean common mosaic virus (BCMV, genus Potyvirus) isolate VN/BB2-5. Based on demarcation criteria, including the genome sequence and host range, we tentatively designate this isolate as BCMV-IYbn (Indonesian yam bean). The nucleotide sequence reported is available in the DDBJ/EMBL/GenBank databases under accession number AB289438.     

Systemic necrosis in tomato induced by a Japanese isolate of rehmannia mosaic virus in a temperature-sensitive manner

The Japanese isolate of rehmannia mosaic virus (ReMV-J) was initially isolated from chilli pepper in Japan. The leaves of diseased chilli pepper plants, which hold no tobamovirus-resistance genes, have mosaic symptoms. As the symptoms progress, the infected plants develop prominent leaf necrosis and severe leaf fall, followed by stem necrosis and fruit distortion. Additionally, ReMV-J systematically infects tomato and this reportedly leads to mottle in tomato when incubated at 20 °C. This study found that ReMV-J induces systemic necrosis of tomato – except for cultivar Micro-Tom – when incubated at 25 °C. To determine the virus factor involved in the induction of temperature-sensitive systemic necrosis on tomato, intergenic recombinants between ReMV-J and tomato mosaic virus were constructed. All recombinant viruses systemically infected tomato similar to ReMV-J. Recombinant viruses with the movement protein (MP) gene of ReMV-J induced systemic necrosis on tomato. Incubation at 20 °C significantly reduced the ability of recombinant viruses with the MP gene of ReMV-J to induce systemic necrosis. Thus, the ReMV-J MP gene is involved in the temperature-sensitive induction of systemic necrosis on most tomato cultivars tested. This study is the first to report the involvement of the MP gene in temperature-sensitive induction of systemic necrosis by tobamovirus on tobamovirus-susceptible tomato.