-58- 



and standard absorption procedures are inadequate. In 

 some cases, the bright autof luorescence of lignified cell 

 walls of certain tissues interferes with observation and 

 photography of specific fluorescence in tissues. Yet 

 another problem in this procedure is that it is difficult 

 to obtain satisfactorily thin ( 1 5 /am or below) sections of 

 plant tissues. In this study, non-specific staining was 

 eliminated by incubating TRITC-con jugated antisera with 

 healthy tissue extracts before staining infected tissues. 

 With healthy tissue extracts and conjugated antibody 

 prepared in advance, the procedure from diseased plant to 

 microscopic examination can be completed in less than 2 

 hours. This is much shorter than the time required for 

 the immunofluorescence procedures described by others 

 (Mumford and Thornley, 1977; Nishiguchi et a_l . , 1980; Rao 

 et al. , 1978) . 



Ferritin and colloidal gold labelled antibodies are 

 the most common probes used for localization at the 

 electron microscopic level (Gildow, 1982; Martelli and 

 Russo, 1984; Baker et a_l. , 1985). Labelling of ultrathin 

 sections with colloidal-gold conjugated antibodies is 

 generally accomplished with less nonspecific binding than 

 when ferritin is used ( De Mey, 1984; Baker et a_l . , 1985). 

 In animal virology, several studies have been performed 

 using the protein A-gold approach in order to trace the 

 place of synthesis, the post-translational glycosylation, 



