Localization of glycopeptides and race-variable polypeptides in urediosporelings and urediosporeling walls of Puccinia graminis tritici; affinity to concanavalin A, soybean agglutinin, and Lotus lectin

Abstract

Detergent-soluble polypeptides from urediosporelings and purified germ-tube walls of urediosporelings of wheat stem rust, Puccinia graminis f.sp. tritici, races C1(17), C17(56), and C36(48) were separated by two-dimensional isoelectric focusing – polyacrylamide gel electrophoresis. More than 280 polypeptides were distinguished by Coomassie brilliant blue staining in each race, and there were 18 polypeptides that varied among the three races, 7 of which were coincident with urediosporeling wall polypeptides. Polypeptides transferred from two-dimensional gels onto nitrocellulose membrane were either stained with India ink or probed with concanavalin A – peroxidase for the location of concanavalin A binding glycoproteins. Of 97 concanavalin A binding glycoproteins in urediosporelings, 41 were coincident with polypeptides that stained with Indian ink and 3 were coincident with race-variable polypeptides. The walls of urediosporelings contained few polypeptides that stained with Coomassie brilliant blue or India ink, but most were concanavalin A binding. None of the polypeptides had affinity to soybean agglutinin or Lotus lectin, suggesting that galactose or fucose is not a terminal sugar moiety in these polypeptides. We conclude that race-variable polypeptides are located both within the cytoplasm and in the walls of urediosporelings, but most are not glycosylated.