ELICITOR-ACTIVE GLYCOPROTEINS IN APOPLASTIC FLUIDS OF STEM-RUST-INFECTED WHEAT LEAVES

Cell walls of germ tubes from wheat stem rust (Puccinia graminis f. sp. tritici) contain a glycoprotein with a molecular mass of about 67000 referred to as the Pgt elicitor. This glycoprotein induces a hypersensitive-like response in wheat leaves. In elicitor-active intercellular washing fluid (IWF) from compatible wheat-stem rust interactions we detected several elicitor-active glycoproteins. One of these glycoproteins had an electrophoretic mobility identical to the Pgt elicitor. This IWF-glycoprotein exhibited elicitor activity upon elution from SDS gels. It was recognized by anti-Pgt elicitor antiserum suggesting partial structural identity between the Pgt and IWF elicitors. As with the Pgt elicitor, the elicitor-activity of the IWF glycoprotein resides in the carbohydrate moiety because periodate, but not trypsin or pronase, destroyed activity. These results suggest that the Pgt elicitor is released from hyphal cell walls into the wheat apoplast during stem rust infection. © 1992.