Microstructure of the skin of d'Agen plums

The skin of mature d'Agen plums (Prunus domestica L.) was investigated by cryo-scanning electron microscopy. Regions of the surface of the fruit were differentiated by the presence or otherwise of a waxy bloom. The epicuticular wax consisted of an underlying amorphous wax layer adjacent to the cuticle proper together with crystalline granules of wax protruding from the surface. Over non-bloom regions of the skin the number and size of the granules were small and the underlying amorphous wax layer predominated. Differences between bloom and non-bloom regions of the skin were attributed to variations in the microclimate of fruits, such as incident radiation. The cuticular membrane was >5 mu m thick. The cuticular layer showed layering, but the lamellation of the cuticular layer, as observed by SEM, did not correspond to any recognised cuticle structural types based on light microscopy and transmission electron microscopy of plant cuticles. Fractures of the epicuticular wax layer frequently formed along the long axis of the stomatal guard cell pair. Localised water loss and collapse of dermal cells occurred in the area around stomata with large fractures. (C) 1999 Elsevier Science B.V. All rights reserved.