Systemic Resistance to Bean Rust Induced in Phaseolus vulgaris by the Preinoculation with Colletotrichum lindemuthianum

Abstract

Preinoculation of the primary leaves of bean plants (Phaseolus vulgaris) with Colletotrichum lindemuthianum (bean anthracnose) at concentrations above 5.0×10⁴ conidia per ml inhibited the development of boan rust (Uromyces appendiculatus) on the first trifoliolate leaves.
The induced resistance was systemic being expressed by decrease in the number of uredia, retardation of formation and maturation of uredia, and reduction of the size of uredia and chlorotic halos surrounding the uredia. The preinoculation of one of the primary leaves with C. lindemuthianum also inhibited the development of bean rust on the opposite primary leaf. Although the size of uredia and chlorotic halos surrounding the uredia were reduced, the number of uredia was not decreased, and the formation and maturation of uredia were not retarded.