Sugar cane arginase competes with the same fungal enzyme as a false quorum signal against smut teliospores

Abstract

Sugar cane cultivars resistant to smut produce a pool of glycoproteins after experimental infection, one of them develops arginine activity. This arginase induces cytoagglutination of smut teliospores but impedes germination. Teliospores also secrete a fungal arginase that accelerates their own germination. This fungal arginase binds to teliospore cell walls. The affinity of this arginase for the ligand shows to be higher than that found for plant arginase. In fact, fungal arginase removes sugar cane arginase previously bound to their ligands in the cell wall whereas the inverse process is practically negligible. The enzymatic activity is required to the binding of the protein to teliospore cell wall but it is not related to the germination process. Thus, it can be concluded that the binding of fungal arginase to smut teliospores activates a signal transduction cascade that enhances germination.