Chapter 5 - Attack Mechanisms of the Pathogen

Abstract

This chapter concentrates on the secretion of extracellular enzymes and toxins, which are the two major attack means with which the pathogen may be equipped, and the ability of the pathogen to detoxify host defense compounds. It also defines the cutinase enzyme, which hydrolyzes the primary alcohol ester linkages of the polymer. Cutin is found in many plant pathogenic fungi, including Botrytis cinerea. However, the importance of this enzyme for penetration of the cuticle seems to be a matter of debate. Many lines of evidence suggest that cuticular penetration of Colletotrichum gloeosporioides into the host is associated with the induction of extracellular cutinase production, and that insertion of the cutinase gene into this pathogen facilitates infection of an intact host. The chapter also explains the pectic substances, which constitute an important component of the primary cell wall of plants, and form the major component in the middle lamella, which are responsible for the tight link between the cells and the integrity of the plant tissue.