Substrate Hydrophobicity and Adhesion of Uromyces Urediospores and Germlings

Terhune, B. T., and Hoch, A. C. 1993. Substrate hydrophobicity and adhesion of Uromyces urediospores and germlings. Experimental Mycology 17, 241-252. Adhesions of urediospores and urediospore germlings of Uromyces appendiculatus, the bean rust pathogen, to various substrata was evaluated with regard to surface wettability. A range of surface wettabilities, or conversely hydrophobicities, was obtained by coating glass or quartz substrates with various organosilanes. Adhesion of urediospores or germlings was evaluated after the spore or germling laden-silanized surfaces were washed. Both urediospores and germlings adhered most tenaciously to surfaces with wettability ratings less than 30. Such surfaces were polystyrene and glass treated with dimethyldichlorosilane, (tridecafluoro-1,1,2,2-tetrahydrooctyl)-1-trichorosilane, and diphenyldichlorosilane. The degree of germling contact to the various surfaces correlated closely with hydrophobicity and with the adhesion of germlings. Induction of appressoria on quartz substrates bearing inductive topographies (0.5-μm-deep grooves) was also closely associated with the degree of hydrophobicity.