Cell Enlargement and Cell Separation During Peach Fruit Development

The increase in cell size and the activities of cell wall lytic enzymes during fruit growth supported by the mesocarp cell enlargement have been studied in peach of the freestone cultivar Redhaven. Four growth stages (S 1-S4) in peach fruit were observed. Cell enlargement and formation of intercellular spaces in the mesocarp were directly correlated with the increase in fruit diameter. Cellulase and exopolygalactu- ronase showed the highest activity during the first stage of fast fruit growth (SI), while the endopolyga- lacturonase activity increased during the last growth stage (S4), when the fruit reached its final size and ripening started.