Development of systemic TMV infection in upper noninoculated tobacco leaves after differential temperature treatment.

A differential temperature treatment (DTT) of infected plants ensured a partial synchronization of the process of tobacco mosaic virus (TMV) infection. The "infectious entity" enters (and spreads to) basal areas of the upper noninoculated leaves held at low temperature, and then to a distal part of these leaves and basal sites of the lower leaves. The spread of the "infectious entity" over the vascular system of the upper leaves could be followed.