Bull. Spec. CORESTA Congress, Brighton, 1998, p. 125, P11

Induction of natural defence systems of the tobacco plant by use of elicitors: a survey of new possibilities of pathogen and pest control

EBERHARDT H.-J.; WEGMANN K.
Verband des Cigarettenindustrie, Bonn, Germany.
During infection of a tobacco plant by a pathogen, a swift defensive reaction against the harmful microorganism or virus may be triggered in the case of an incompatible interaction. A decisive element in the plant's defence system is the induction of a mechanism known as 'Systemic Acquired Resistance' (SAR). It is responsible for the development of a lasting resistance which extends to subsequent infections by the same or even unrelated pathogens. SAR is induced by elicitors. These are signal substances released during interaction between host and pathogen which involve a number of local or systemic defensive measures of the plant. Salicylic acid (SA) is such an elicitor and at the same time an important component of the SAR signal chain which brings about the development of a resistance by stimulation and expression of certain defence-associated genes. Benzothiadiazole (BTH), a synthetic compound which imitates the natural inductive properties of SA, is already being used in agriculture and thus belongs to a new generation of agrochemicals which work indirectly. These inductors of natural resistance mechanisms open up interesting alternatives to the use of conventional synthetic pesticides or recombinant DNA technologies. The following survey will present various SAR elicitors ( e.g. , SA, BTH, oligogalacturonides, glucans, chitosans, elicitins, UV-irradiation) and discuss the possible use and significance of chemical or physical activators of the plant's defence systems for tobacco growing.