Effects of Concanavalin a on the Germination of Smut Teliospores and on the Hyphal Growth

Abstract

Sporisorium scitamineum cells, that causes smut disease in sugar cane, respond to Concanavalin A (ConA). This lectin stimulates the cytoagglutination of teliospores, an excessive elongation of germinative tubes and induces morphological changes in hyphae, in the same way that it occurs in other cellular types. These events seem to play a defensive role in plants against pathogenic infections. In fact, ConA prevents S. scitamineum germination. Binding assays reveal that the distribution of ConA specific receptors is heterogeneous in both location and stage of cycle. Generally, it seems that the lectin activates mitotic events during the life cycle of cells that have been previously able to germinate. For example, increased cell budding is observed in released sporidia after contact with high concentration of the lectin. Moreover, desorption assays indicate that bound ConA is partially desorbed by methyl-mannose and by sugar cane glycoproteins, suggesting that important polysaccharide ligands involved in the defensive response against smut disease could be contained in sugar cane juice produced by resistant varieties.