Purification and properties of ginger chlorotic fleck virus

A previously undescribed isometric virus, named ginger chlorotic fleck virus (GCFV), was detected in ginger (Zingiber officinale) imported into Australia from a number of countries. The geographical distribution of the virus is uncertain, but is thought to include India, Malaysia and Mauritius. The virus apparently does not occur in Australian commercial ginger plantings. The virus has isometric particles c. 30 nm in diameter, with a sedimentation coefficient of 111 S, and was readily purified from infected ginger with yields of 50–90 mg/kg leaf tissue. Purified preparations contained a major species of single-stranded RNA of mol. wt 1.50 × 10⁶ and a major coat protein species of mol. wt 29.0 × 10³. At pH 7, the particles formed a single zone in both caesium chloride and caesium sulphate gradients, with buoyant densities of 1.355 g cm^-3 (fixed virus) and 1. 297 g cm^-3 (unfixed virus), respectively. The virus particles migrated as two electrophoretic components and were labile when treated with 10 mM EDTA, 1 M NaCI, 10 mM tris pH 8.25 or when negatively stained with potassium phosphotungstate. GCFV was mechanically transmitted only to ginger, and was not transmitted by the aphids Myzus persicae. Pentalonia nigronervosa, Rhopalosiphum maidis or R. padi. Possible affinities of GCFV with the sobemo-virus group are discussed. The present cryptogram of GCFV is ^R/_l: ^1.5/₂₀: ^S/_S: ^S/_*.