Bean dwarf mosaic virus : a model system for the study of viral movement

SUMMARY Taxonomy: Bean dwarf mosaic virus ‐[Colombia:1987] (BDMV‐[CO:87]) is a single‐stranded plant DNA virus, a member of the genus Begomovirus of the family Geminiviridae . Physical properties: BDMV virions are twinned incomplete isosahedra measuring 18 × 30 nm. The viral particle is composed of 110 subunits of coat protein, organized as 22 pentameric capsomers. Each subunit has a molecular mass of ∼29 kDa. BDMV possesses two DNA components (designated DNA‐A and DNA‐B), each ∼2.6 kb in size. Host range: The natural and most important host of BDMV is the common bean ( Phaseolus vulgaris ). Nicotiana benthamiana is often used as an experimental host. Common bean germplasm can be divided into two major gene pools: Andean materials, which are mostly susceptible to BDMV, and Middle American materials, which are mostly resistant to BDMV. Disease symptoms: The symptom intensity in common bean plants depends on the stage of infection. Early infection of susceptible bean seedlings will result in severe stunting and dwarfing, leaf distortion and mottling or mosaic, as well as chlorotic or yellow spots or blotches. BDMV‐infected plants usually abort their flowers or produce severely distorted pods. Late infection of susceptible plants or early infection of moderately resistant genotypes may show a mild mosaic, mottle and crumpling or an irregular distribution of variegated patches. Biological properties: As a member of the Begomovirus group, BDMV is transmitted from plant to plant by the whitefly Bemisia tabaci . BDMV is a nonphloem‐limited virus and can replicate and move in the epidermal, cortical and phloem cells. As a nonphloem‐limited virus, it is sap‐transmissible.