Elicitor of lignification

Figure 1. Hypothetical scheme of events leading to race-cultivar specific resistance or susceptibility in the rust system. If the substrate specificity of the fungal cell wall degrading enzymes (e.g., pectinases) is suitable for degradation of a specific host cell wall component (e.g., partly esterified pectin), endogenous suppressors will be produced which prevent the elicitor induced lignification response, thus leading to susceptibility.

They act as antipathogenic agents and thus affect the process of pathogenesis. They may act on the host through the Induction of plant resistance mechanisms such as stimulation of lignification or enhancement of phytoalexin production. (Please refer to the chapter by Salt and Kuc in this volume for further discussion of this type of compound.) They may act on the pathogen to accentuate elicitor release or to prevent infection (host penetration), colonization (inhibition of phytotoxin synthesis, extracellular enzyme production and action, or phytoalexin degradation) or reproduction. 

The term elicitor, initially defined as a fungal metabolite capable of inducing phytoalexin production when applied to host plants (122, 123), has since been applied to parasite-derived molecules which induce any facet of resistance in appropriate host plants, including lignification (124). 

When injected into primary leaves of different cereals, the stem rust elicitor causes symptoms which closely resemble the respective resistance reactions of these species against the attack by stem rust of wheat, i.e., lignification in barley and rye, brown spots in oat, and no visible symptoms in maize (66). 

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