Protein‐bound Sulfhydryl Groups in Coleus Wound Meristems

R oberts , L orin W. (U. Idaho, Moscow.) Protein‐bound sulfhydryl groups in Coleus wound meristems. Amer. Jour. Bot. 47(2): 110—114. Illus. 1960.–A hisiochemical examination was conducted of the development of the stem wound‐meristem of Coleus blumei Benth. with 2,2‘‐dihydroxy‐6,6‘‐dinaphthyl disulfide (DDD) and 1‐(4‐chloromercuriphenylazo)‐naphthol‐2 (Mercury Orange) to test for protein‐bound sulfhydryl groups. Specificity for the histochemical reactions was indicated by complete blocking of staining in sections pretreated with 0.001 M iodine in npropanol and 0.1 M aqueous solutions of iodoaceiamide. Both histochemical methods yielded comparable results in protein‐SH localization (zone of cell division and differentiating xylem elemments) and staining intensity. The zone of cell division did not exhibit staining at the time of initial cell division (3 days). However, the cytoplasm of the dividing cells of the wound‐meristem demonstrated protein‐SH 4—5 days following wounding. A high concentration of protein‐SH was observed in the cytoplasm of the dividing cells 7 days after wounding. Redifferentiating parenchyma cells, destined to become wound‐xylem elements, first exhibited wall staining at the time of protoplast contraction. The subsequent walled xylem stage exhibited strong staining in the reticulated striations of the secondary walls.