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

Abstract

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.