Identification of amino acid residues of Fusarium verticillioides endo-polygalacturonase required to escape the inhibition by host plant PGIP

Endopolygalacturonases (Endo-PGs) play an important role in fungal infection since they depolymerize the pectin component of plant cell wall. Most plant have evolved defence mechanisms to contrast the action of endo-PGs. A direct mechanism is the interaction with plant cell wall polygalacturonase-inhibiting proteins (PGIPs) that block polygalacturonase activity. However, fungal pathogens can elude the inhibition by plant PGIP, producing PGs refractory to inhibition. Fusarium verticillioides endo-PG is unaffected by host PGIPs (asparagus and leek) as well as by Phaseolus vulgaris PGIP, that is the most efficient PGIP so far characterized. Recently, we have identified a specific PG amino acid residue responsible for the lack of recognition by bean PGIP. Now we have mutated few amino acids of the F. verticillioides endo-PG which allow the recognition by host PGIP. This finding highlights the structural features of the enzyme to escape PGIP inhibition. Moreover, this modified PG could be used to replace native F. verticillioides PG in order to better clarify the role of constitutive PGIP in plant defense.