Association ofPestalotia malicolawith the plant cuticle: visualization of the pathogen and detection of cutinase and non-specific esterase

The fungus Pestalotia malicola attacks fruits of Chinese quince ( Chaenomeles sinensis ) in Japan. Scanning electron microscopy (SEM) in combination with micromanipulation as well as cryo SEM demonstrated that the fungus was growing on, within, and beneath the fruit cuticle. The ability of the pathogen to grow in association with the cuticle suggested that the fungus produces cutinase(s) and/or non-specific esterase(s). Enzyme assays revealed that the fungus produced an enzyme, or enzymes, with activities characteristic of a cutinase and a non-specific esterase when cultured on cucumber cutin as the sole carbon source. The same enzyme activities were also demonstrated to be constitutively present in the extracellular matrix that surrounds conidia in conidiomata.