CARBOHYDRATES ON THE SURFACE OF UREDINIOSPORE-DERIVED AND BASIDIOSPORE-DERIVED INFECTION STRUCTURES OF HETEROECIOUS AND AUTOECIOUS RUST FUNGI

Nine fluorescein isothiocyanate-labelled lectins with affinity towards different carbohydrates were used to probe the surface carbohydrates of infection structures in vitro, derived from urediniospores and basidiospores of an autoecious rust species, Uromyces viciae-fabae (Pers.) Schroet., and of a heteroecious rust species, Uromyces rumicis (Schum.) Wint. Lectin binding was quantified by measuring fluorescence photometrically. All lectins bound in a characteristic pattern to the infection structures of the respective spore types of each rust fungus. Differences were especially obvious between those infection structures normally produced inside leaf tissue, namely the urediniospore-derived substomatal vesicles with infection hyphae, and the basidiospore-derived intraepidermal vesicles. The dikaryotic stage and the monokaryotic stage of the heteroecious fungus differed mainly in their affinity for the lectins from Bandeira simplicifolia and Lotus tetragonolobus. A statistical analysis comparing the binding of the lectins to infection structures of two rust fungi suggested that cell surface composition is determined by nuclear condition. The monokaryotic stages of both rust fungi have a higher degree of similarity than the dikaryotic and monokaryotic stages of the same rust fungus.