Eventos dos processos de pré-penetra？？o, penetra？？o e coloniza？？o de Phakopsora pachyrhizi em folíolos de soja

light (le) and scanning electron microscopy (sem) were used to study the development of phakopsora pachyrhizi from urediniospore germination to colonization on soybean. drops of 50 μl of a spore suspension (3 x 104 urediniospores.ml-1) were inoculated on detached leaflets of seven cultivars, besides the genotypes pi 230970 and pi 459025. after inoculation, leaflets were stored in bod at 23 ± 2 ± 2 oc for incubation. samples were taken from four to 240 hours after the inoculation (h.a.i.), submitted to the process of fixation for scanning electron microscopy (sem) and decolorized into a solution of absolute ethanol/acetic acid (1:1, v/v). in decolorized samples differences were observed among cultivars in percentage of germination, appressorium formation and consequently in the penetration. on pi 429025 the lowest percentage of germinated urediniospores (20%) and of appressoria formation (11 %) was observed, and the cultivar brs 154 presented a higher percentage of both germination (85.5 %) and appressoria formation (66.5 %). among other cultivars the percentage of germination was from 42% to 73.5 % and from 21.5 to 60.5 % for appressoria formation. several events in the colonization process observed by sem were different from those in the literature.