STRUCTURE OF EPIDERMIS WALL, CUTICLE AND CUTICULAR MICROCRACKS IN NECTARINE FRUIT

The fine structure of the epidermis of the nectarine fruit ("Tasty-fruit" cultivar) has been investigated. The work was mainly focussed on cuticular microcracks which occur on the ripe fruit. The outer wall of the epidermal cell is thick and is composed of different layers which exhibit various textures. A layer that could be interpreted as a cutinized, dense network of polysaccharidic fibrils, clearly appears at the junction between the cuticle and the wall. Cracks result in an abrupt interruption of the cuticle, but the layer at the junction of the cuticle and the wall and in some instances the waxes remain at the surface of the cell wall. The wall itself shows the same aspect in the cracks and under the normal cuticle. The susceptibility of cracks to the penetration by phytopathogenic fungi is discussed.