ASSOCIATION OF PESTALOTIA-MALICOLA WITH THE PLANT CUTICLE - VISUALIZATION OF THE PATHOGEN AND DETECTION OF CUTINASE AND NONSPECIFIC ESTERASE

The fungus Pestaiotia malicola attacks fruits of Chinese quince (Chaen omeles sinensis) in Japan. Scanning electron microscopy (SEM) in combi nation with micromanipulation as well as cryo SEM demonstrated that th e fungus was growing on, within, and beneath the fruit cuticle. The ab ility of the pathogen to grow in association with the cuticle suggeste d that the fungus produces cutinase(s) and/or non-specific esterase(s) . Enzyme assays revealed that the fungus produced an enzyme, or enzyme s, with activities characteristic of a cutinase and a non-specific est erase when cultured on cucumber cutin as the sole carbon source. The s ame enzyme activities were also demonstrated to be constitutively pres ent in the extracellular matrix that surrounds conidia in conidiomata. (C) 1998 Academic Press.