Functions and mechanisms: polygalacturonases from plant pathogenic fungi as pathogenicity and virulence factors

Polygalacturonases (PGs) are widely distributed pectic enzymes in microorganisms that are plant pathogens, and those that are not plant pathogens, and in plants themselves. PGs degrade the adhesive pectic substances of the middle lamella and cell wall, contributing to fungal penetration, plant tissue collapse and nutrient acquisition. Not all PGs that are produced by plant pathogens are required for pathogenicity or virulence, and PGs are present in nonpathogens. This review provides an overview of the functions and mechanisms of PGs in the pathogenicity and virulence of fungi and interpretations of the keys to PG involvement in pathogenesis.