Histochemical studies of tannin accumulation in root and seed of buckwheat.

Abstract

This study was conducted to investigate the localization of tannin in the roots and seeds of buckwheat. Tannin was histochemically detected by the treatment of ferric chloride solution. Results were summarized as follows : 1. Tannin was detected in the stele of seminal root at the early growth stage as 11th day after sowing (Figs. 1 and 2). 2. The content of tannin decreased in the stele and increased in the cortex of lateral roots at the 18th day after sowing (Fig. 3). After 27 days, tannin mostly accumulated in the (cortex (Fig. 4). 3. Tannin accumulation in the cortex reached to maximum in lateral roots at the 33th day after sowing (Fig. 5). 4. Tannin was detected also in cortex of brace root and fine fibrous root (Figs. 6, 7, 8 and 9). 5. Coloration of tannin was also detected in immature seeds in the same lebel as in mature ones, but the sensitivity to detect tannin decreased by FAA fixation (Figs. 10A and 10B). 6. In mature seeds, tannin was localized in their outer seed coats, and tannin was first detected in brown seed coats at the bottom of the immature ones (Figs. 11 and 12). 7. Tannin was distributed within their pigment layers in the immature pericarp and within the inside parenchyma of the mature one, which corresponds to pigment layers of immature one (Figs. 13 and 14). 8. High content of tannin was detected in their basal parts of calyx in which the tannin was distributed in the epidermis of their adaxial side (Figs. 15 and 16).