Structural changes in the abscission zones of pedicels at different ripening stages of tomato

Abstract

Structural changes in abscission zones on tomato pedicels were anatomically and histochemically investigated. One week after the onset of the fully ripe stage of fruit development, cells of the xylem parenchymatous region in the primary abscission zone which formed at the flower bud stage elongated longitudinally more than those of the adjacent cells. Ten days later, the elongated cells formed in the primary abscission zone, but their walls hydrolyzed in two weeks, leaving large intercellular cavities. Fruit abscission then occurred. Simultaneously, cells became lignified in the secondary cell division zone, on the proximal side of the abscission zone. No further development occurred until the fruit abscised. These results indicate that the primary abscission zone acts as the separation layer, whereas the lignified secondary cells act as the protective layer.