Induced Protection against Wildfire Disease in Tobacco Leaves treated with Heat-killed Bacteria

Abstract

PLANT tissues infected with viruses and fungi are often protected against re-infection with the same or another pathogen^1–4. Multiplication in the host tissues of micro-organism(s) of the primary infection appears to be a pre-requisite of these protective actions. Recently Loebenstein succeeded in inducing partial protection of the host against viral infection by treating the host tissues with the protein part of the infective virus particle⁵. This indicates that, at least in some cases, the multiplication of the pathogenic agent is not necessary for the development of the protective effect. A phenomenon somewhat similar to that observed by Loebenstein is described in the present report. It has been shown that the pretreatment of tobacco leaves by heat-killed bacteria induces protection against infection by Pseudomonas tabaci (Wolf and Foster) Stevens.