The Inhibition of Virus Increase by Malachite Green

Abstract

By a detached leaf tissue method (Takahashi, in press), the effect of low concs. of malachite green on the increase of tobacco mosaic virus in leaf tissue was studied. One-gm. strips from infected half-leaf prepns. were used, one set floated on malachite green and the other on dist. water. The expts. were done in the dark and terminated after 8 days of culture. To detn. the extent of virus formation, the tissues were homogenized, diluted 1 part in 20 with dist. water, and inoculated on 20 opposite halves of Nicotiana glutinosa leaves. Considerable inhibition of virus increase was shown at concs. of malachite green as low as 2 ppm., and more at 4 ppm. The number of local lesions on 20 half-leaves for leaf tissue on 2 ppm. was 70, and for the control on distd. water, 312. At 4 ppm. the totals were 46 for treated and 1,068 for control. At the concs. used, malachite green had practically no effect on the extracted virus in vitro. A treated suspension of virus (4 ppm. of malachite green) gave 1,890 local lesions, and the control, 2,060.