Micromorphological, anatomical and ultrastructural analyses of ovaries and fruitlets indicate early qualitative differences in two Prunus domestica cultivars

The aim of this study was to investigate if there are the differences in development of qualitative traits of fruits in two cultivars of Prunus domestica: 'Bluefre' and 'President', which may affect the quality of ripe fruit. The micromorphology, anatomy, and ultrastructure of ovaries during the anthesis phase as well as the pericarp of 28-day-old fruitlets of these cultivars were analysed using light, scanning electron, and transmission electron microscopy. The results showed that the initiation of development of some quality fruit characteristics as well as cell growth were largely determined in the ovary during the anthesis phase and in the fruitlet stage. In addition to many similarities, a number of quantitative and qualitative differences were found between the two cultivars in both developmental stages. Differences detected in both the outer and the inner cell layers were associated with time of initiation and the rate of development of traits that may determine quality and storability of mature fruits. The most important fruit quality traits analysed were production of wax bloom, development of stomata, thickening of the cuticle and epidermal and hypodermal walls, and deposition of phenolic compounds, mainly tannins.