Sugarcane glycoproteins bind to surface, specific ligands and modify cytoskeleton arrangement of Ustilago scitaminea teliospores

Abstract

Inoculation of sugarcane plants, cv. Jaronu 60-5, with teliospores of Ustilago scitaminea increased the production of sugarcane glycoproteins of high molecular mass (HMMG) and decreased the amount of those of mid-molecular mass (MMMG) recovered from stalks cell-free extracts. Whereas sugarcane glycoprotein of healthy plants totally inhibited the production of fungal mycelium from teliospores, mycelium growth was slightly affected by MMMG, and drastically diminished by HMMG obtained from inoculated plants. The adhesion of sugarcane glycoproteins to fungal teliospores produced cell aggregation. This effect was clearly reduced by incubating teliospores in buffer containing HMMG or MMMG previously digested with invertase. Sugarcane arginase associated to MMMG was retained by teliospores, whereas the enzymatic activity associated to HMMG from inoculated plants increased. Chitinase was not significantly retained by teliospores. Only HMMG and MMMG obtained from healthy plants were able to inhibit cell polarity in some extent. Smut induced changes in the composition of HMMG and MMMG. Some of these new glycoproteins are able to inhibit cell polarity. Since receptors, isolated from the cell wall of smut teliospores, were eluted from activated agarose beads by N-acetyl-D-glucosamine, we concluded that the peptide fraction of HMMG and MMMG bind to this amino sugar in the polysaccharide moiety of smut ligands.