LOCALIZATION OF ABSCISIC-ACID BINDING-PROTEINS IN MAIZE ROOT-TIP USING IMMUNOGOLD-SILVER STAINING METHOD

Antisera against abscisic-acid-binding proteins (Ab I) and anti-idioty pic antibodies to ABA monoclonal antibody (Ab II) have been developed and tested to comparatively localize abscisic-acid-binding proteins (A BBPs) in maize root tips using immunocytochemistry technique. Based on the staining pattern observed along the root tip, an apicobasal gradi ent of ABBP has been revealed with either Ab I or Ab II. The labels ar e mainly concentrated is the root cap and apical meristem. In the elon gation zone and root hair zone, only cells in pericycle and epidermis are obviously labeled. The silver labels are distributed evenly in the whole cell of the apical meristem, but in the cells of the root cap a nd elongation tenet the positive staining degree in the cytoplasm is r educed even to completely negative staining; nevertheless, the nuclei and plasma membranes are strongly labeled. As in the labeled cells of the root hair zone, only some immunoactive sites can be seen in the nu cleus compacted to the edge of the cells. The staining pattern in the whole root tip also shows obvious dependence of the ABBPs localization on the activity of the nucleus. The significance of ABBPs localizatio n is discussed.