CHARACTERIZATION OF A RHIZOCTONIA ZEAE POLYGALACTURONASE AND ITS INTERACTION WITH THE PLANT INHIBITOR PvPGIP2.

The plant cell wall, the main structural element that a pathogen needs to overcome in order to penetrate and colonize the plant tissue, is composed by four major complex polysaccharides (cellulose, hemicellulose, lignin, and pectin). The majority of pathogenic microorganisms produce cell wall degrading enzymes (CWDEs) that are essential for the invasion process. Among the different CWDEs produced by fungi polygalacturonases (PGs) play a critical role since their action on pectin makes other cell wall components more accessible to other CWDEs and causes tissue maceration. To limit the aggressive potential of PGs, plants have evolved small gene families encoding polygalacturonase-inhibiting proteins (PGIPs). The PG–PGIP interaction retards the hydrolysis of pectin but also favors the accumulation of oligogalacturonides (OGs) that activate the plant innate immunity system. Here we present the purification and characterization of a PG from R. zeae and its ability to interact with PvPGIP2.