Stimulation of tobacco mosaic virus synthesis by phenobarbital

Abstract

The stimulative effect of phenobarbital (PB) on tobacco mosaic virus (TMV) synthesis in tobacco leaves was studied. PB of 50 ppm stimulated TMV synthesis by 40%, whereas the number of local lesions produced on Nicotiana glutinosa, Nicotiana tabacum cv. Xanthi, nc., and bean (Phaseolus vulgaris cv. Otenashi) was not altered by PB treatment. PB did not significantly affect the RNA content of tobacco leaves ; however, ribonuclease (RNase) activity in tobacco leaves infected with TMV or uninfected was increased by PB treatment. NADPH oxidase activity in tobacco leaves was increased and peroxidase activity in tobacco and bean leaves was inhibited, both by PB treatment. Mixed treatment of tobacco leaves with PB and plant hormones, such as indole acetic acid (IAA) or Kinetin, caused a reduction in TMV titer and NADPH oxidase activity as compared with the treatment of PB alone. The mechanism of the stimulation by PB of TMV synthesis in tobacco leaves is discussed.