[Induction of plant resistance to the tobacco mosaic virus with a double-stranded poly(G)-poly(C) complex]

Inoculation of double-stranded polyribonucleotide poly(G) . poly(C) complex in a concentration of 50-200 micrograms/mg into tobacco and thornapple leaves was found to produce resistance of the plants to subsequent infection with tobacco mosaic virus (TMV) manifested in decreased number and size of local virus lesions. The induced resistance may spread over the plant and be found in the upper untreated leaves. The level of systemic resistance, however, is much lower than that of the resistance demonstrated in the injected leaves. Actinomycin D (5 micrograms/ml) had no significant effect on the number but stimulated the growth of lesions developing in leaves injected with poly(G) . poly(C) as well as increased their number in the upper leaves of the same plants proximal to the treated ones. Development of tobacco resistance to TMV was accompanied by changes in the activity of terminal oxidases, particularly peroxidase. Possible mechanisms of formation of induced resistance are discussed.