Mosaic Disease of Tobacco

Abstract

An aqueous solution of safranin precipitates the virus of tobacco mosaic from juice of diseased plants. This precipitate brings down practically all of the virus. The virus is apparently held in an inactive condition in the precipitate, but is released when the safranin is removed by means of amyl alcohol. Material which gives an infectious solution when redissolved in water has been salted out of infectious juice with (NH4)2SO4 and with MSO4. Two volumes of acetone or alcohol, when added to 1 volume of juice from diseased plants, at about 0[degree]C, throws down a precipitate which contains practically all of the virus. Juice from Turkish tobacco plants with mosaic disease contains 2 well-defined heat precipitable fractions. One comes down around 85[degree] C. and the other above 90[degree] C. Only the 1st fraction contains an appreciable amount of N. The juice remains infectious after removal of the 1st fraction, although the virus concentration is greatly reduced. Some of the phosphate, sulphate, and most of the protein and pigment may be removed from juice of diseased plants with low concentrations of Pb acetate and Ba acetate without apparently removing or injuring the virus. Juice from diseased plants, after clearing with Pb acetate and Ba acetate, may be concentrated in vacuo below 50[degree] C. without apparent injury to the virus. Cleared juice from diseased plants concentrated in vacuo to 0.4 the original volume and brought to about 0[degree] C. gives a precipitate when two volumes of acetone at -15[degree] C. are added. This precipitate contains only about 10% of the solids of the original juice, but apparently contains all of the original virus. The behavior of the virus is in many ways analogous to that of a chemical substance.