MORPHOLOGICAL CHARACTERISTICS UNDER OPTICAL MICROSCOPE OF TANNIN CELLS IN PERSIMMON FRUIT

Persimmon fruit has many tannin cells, which are distinguishable from other fruits. It is important to study tannin cells to elucidate some properties of persimmon fruits. The intact tannin cells of soft-ripe persimmon fruits from 103 close species and cultivars were observed under optical microscope. Tannin cells were classified into six groups by shape as threadlike, long, oblong, polygon, round, and needle-like and into four groups by the performance on the cell as thorn-like, tumor-like, concave, and smooth. Size of tannin cell was usually larger in the mesocarp than in epicarp. Cell types, their composition, and the appearance were also different by fruit portion and cultivar types (PCNA, PVNA, PCA, and PVA). Tannin cells in mesocarp appeared as single units or bundle and agglomerated forms by cultivar types. The color of the cells in PCNA and PVNA cultivars tend to be brown. The brown cells in Japanese origin PCNA cultivars belong to coacervate type, whereas those in Chinese origin PCNA cultivars belong to concretionary type. The brown tannin cells of concretionary type were also observed in astringent cultivars. Such similarity in the tannin cell performance suggested that PCNA cultivars might have been derived from the mutation of astringent cultivars.