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GOLD, R. E., and K. MENDGEN. 1984. Cytology of basidiospore germination, penetration, and early colonization of Phaseolus vulgaris by Uromyces appendiculatus var. appendiculatus. Can. J. Bot. 62: 1989Bot. 62: -2002. Cytological studies were done on a compatible interaction between Phaseolu.\ vulgaris and Uromyces appendiculatus var. appendiculatus. The cytoplasm of germinated basidiospores contained numerous microbodies in close association with lipid bodies. vacuoles, and endoplasmic reticulum. A single, polar germ tube commonly developed from a germinating basidiospore. The germ tubes tended to grow toward or along the junction lines between host epidermal cells. Appressorium formation in ca. 75% of all observations occurred less than 3.5 fLm away from the lines of juncture. A mucilaginous exudate was associated with germ tubes and appressoria along areas of contact between host and fungus. Epidermal wall papillae were often observed beneath basidiospores and appressoria but did not restrict entrance of the fungus. The fungus directly penetrated the epidermal cell and invaginated the host plasma membrane. The apex of the penetration peg expanded to form an ovate intraepidermal vesicle. Electron-opaque material occluded the penetration pore after migration of the usually binucleate protoplast into the vesicle. The intraepidermal vesicle developed apically and formed a multicellular primary hypha that initially was multinucleate and later became uninucleate or binucleate. jonction entre les cellules epidermiques de I'h6te. La formation d'appressorium dans ca. 75% de toutes les observations ont lieu amoins de 3.5 fLm des Iignes de jonction. Un exsudat mucilagineux est associe al'hyphe germinatif et aux appressoriums le long des surfaces de contact entre I'h6te et le champignon. Les papilles des parois epidermiques s'observent souvent sous les basidiospores et les appressoriums mais n'empechent pas l'entree du champignon. Le champignon penetre directement la paroi epidermique et invagine la plasmalemme de I'h6te. L'apex de l'hyphe de penetration se gontle pour former une vesicule intraepidermique ovoi'de. Un materiel opaque aux electrons obstrue le pore de penetration apres la migration du protoplaste usuellement binuclee dans la vesicule. La vesicule intraepidermique se developpe de fa<;on apicale et forme un hyphe multicellulaire primaire qui est multinuclee au depart et plus tard devient uninuclee ou binuclee. L'hyphe primaire se developpe alors dans les cellules epidermiques adjacentes soutendant les cellules du parenchyme palissadique et tapissant les espaces intercellulaires.[Traduit par le journal] Introduction Early studies of host penetration by rust basidiospore germlings were done by DeBary (\863), Reess (1870), Rathay (\881), Ward (\888), Fischer (\898), Eriksson (\911), Robinson (1913), and Waterhouse (\921). Ruth Alien later confirmed and expanded these initial studies with detailed descriptions and illustrations of basidiospore-derived rust infections (1930, 1932a, 1932b, 1934, 1935). Parallel to A...

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Mycology 12, 275-283. The effect of six different substrates on basidiospore germination and differentiation of infection structures was investigated in three species of Uromyces:U. appendiculatus var. appendiculatus, U. viciae-fabae, and U. vignae. Light and fluorescent microscopic observations were made after 3 days of incubation on the following substrates: 2 or 5% water agar, glass slide, collodion membrane, nitrocellulose sheet, and isolated host cuticle. Infection structure development up to the formation of a primary hypha was observed on hard substrates, such as 5% water agar, nitrocellulose sheet, and on isolated host cuticle. Addition of oil to the collodion membrane did not significantly increase the differentiation rate. The morphology and nuclear condition of these basidiospore infection structures were similar to those observed in host tissue. For the three directly penetrating species we studied, it appears that basidiospores respond to an unspecific stimulus, such as the thickness of host cuticle or the hardness of an artificial substrate. o 1988 Academic Press, Inc.

Abstract·The effects of light and host volatiles on teliospore germination in Uromyces appendiculatus var. appendiculatus were studied.

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