Samples from Urediniospores of some rust fungi such as Melampsora epitea, Melampsora medusae, Hemileia vastatrix, Uromyces appendiculatum, Puccinia sorghi, Tranzschelia discolor and Phakopsora euvitis respectively from Salix sp., Populus deltoides, Coffea arabica, Phaseolus vulgaris, Zea mays, Prunus persicae and Vitis vinifera, were processed by three different methodologies for scanning electron microscopy (SEM) observations. These methodologies were: a) conventional methodology (glutaraldehyde and osmium tetroxide fixation, dehydrated in an acetone series, dried in a critical point dryer and sputtered with gold); b) fixation using osmium tetroxide vapor technique and sputtering with gold and c) direct sputtered of the samples with gold (with free urediniospores). Also fractures of leaf sample frozen in liquid nitrogen were used to observe details within the uredia from grape rust (P. euvitis). The samples were observed in a scanning electron microscope (SEM) LEO 435VP and the images were captured and recorded by using the software LeoUserInterface and processed with Corel Photopaint 9.0 software. The dimension of the urediniospores was also measured. Regardless of the technique the structure of the urediniospores were very well preserved resulting in images of high quality. However the technique of direct sputtering was more useful and quick to see the urediniospores. The liquid nitrogen fractures allowed a perfect observation from the interior of the grape rust uredia.
Melampsora epitea; Phakopsora euvitis; Melampsora medusae; Hemileia vastatrix; Uromyces appendiculatum; Puccinia sorgh; Tranzschelia discolor
