Pectin methylesterase (PME) inhibitor involved in the maintenance of cell wall integrity in response to necrotrophic pathogens. Modulates PME activity and pectin methylesterification during infection by Botrytis cinerea and contributes to resistance against the pathogen. Induced in leaves during infection by Botrytis cinerea. No visible phenotype under normal growth conditions, but mutant plants have enhanced susceptibility to infection by the necrotrophic pathogen Botrytis cinerea. Belongs to the PMEI family.