Methyl esterification of pectin plays a role during plant–pathogen interactions and affects plant resistance to diseases

The cell wall is a complex structure mainly composed by a cellulose–hemicellulose network embedded in a cohesive pectin matrix. Pectin is synthesized in a highly methyl esterified form and is de-esterified in muro by pectin methyl esterases (PMEs). The degree and pattern of methyl esterification affect the cell wall structure and properties with consequences on both the physiological processes of the plants and their resistance to pathogens. PME activity displays a crucial role in the outcome of the plant–pathogen interactions by making pectin more susceptible to the action of the enzymes produced by the pathogens. This review focuses on the impact of pectin methyl esterification in plant–pathogen interactions and on the dynamic role of its alteration during pathogenesis.