The development of the grape berry cuticle in relation to susceptibility to bunch rot disease

Some physical and morphological factors of grape berry cuticle were investigated at different developmental stages of three clones of Vitis vinifera cv. Pinot noir, The surface morphology of grape berries was examined by scanning electron microscopy and cuticle anatomy was examined by light and transmission electron microscopy, During the period from flowering to maturity, the composition of the cuticular waxes changed, corresponding with an increase of waxy deposits and significant modifications of the wax surface morphology, The content in cutin per unit surface decreased more than 2.5-fold between berry set (16 d after anthesis) and veraison of the grape berries, and might predispose the grape berry to fungal infection. This result was correlated with the differentiation of the cuticle layers and particularly with a decrease in the thickness of the primary cuticle at harvest.