ULTRASTRUCTURE OF THE CELL-WALLS OF BIGAR REAU BURLAT CHERRIES OF DIFFERENT TEXTURES DURING RIPENING

The changes in texture of fruits during ripening are linked to cell wa ll degradation involving synthesis and degradation of polymers. An inc rease in pectin solubility leads to cell sliding and an elastic aspect of tissues. The biochemical cell wall process differs between soft an d crisp fruits originating from a same cultivar but cultivated under d ifferent agroclimatic conditions. Although the proportions of cell wal l material are similar, the composition and structure of the two cell walls are very different at maturity. A solubilization of the middle l amella and a restructuration of the primary cell walls arising from th e cells separation is observed in crisp fruits. In contrast, the middl e lamella of the soft fruits is better preserved and the primary cell walls are thin and show degradation bags delimited by residual membran e formations. In addition, the macroendocytosis process by endosome in dividualization is more important in soft fruits. In conclusion, the f ruit texture depends on the extent of the links between cell wall poly mers.