Formation of the Secondary Cell Division Zone in Tomato Pedicels at Different Fruit Growing Stages.

Abstract

The abscission zone of the tomato fruit pedicel is initiated by the onset of secondary cell division on the proximal side of pedicels adjacent to the primary abscission zone when the fruit is about 1cm in diameter. Cells of secondary cell division zone which are flat situated in the inner cortex (central parenchymatous region) of the pedicel. The cells have thinner walls than those of the adjacent cells during the early stage of fruit development to the mature-green stage. At the mature stage, these secondary cell walls thicken and become heavily lignified. Cells of the primary abscission zone which form at the flower bud stage are smaller and more densely packed than the adjacent cortical cells which are filled with cytoplasm and unlignified. Therefore, the newly formed secondary cell division zone may partly play a role of a protective layer, whereas the primary abscission zone acts as a fruit separation layer.