Characterization of an infection structure-specific gene from the rust fungus Uromyces appendiculatus.

Uredospores of the plant pathogen, Uromyces appendiculatus, infect leaves of the bean plant, Phaseolus vulgaris, through stomata. Physical stimuli provided by the stomate induce differentiation of the germ tube to form a series of infection structures involved in host colonization. Contact between the uredospores and the oil-collodion membranes induces formation of infection structures in the absence of the host. This report describes the characterization of a Uromyces gene, INF24, that is induced by the physical stimulus of an oil-collodion membrane. INF24 contains a 450-bp open reading frame which encodes a 16.4-kDa polypeptide. The N terminus of the INF24-encoded protein, and the C terminus of human single-stranded DNA-binding protein are both glycine-rich and share homology.