Maize Polyamine Oxidase: Antibody Production and Ultrastructural Localization

Abstract

Summary In this paper we describe the ultrastructural localization of the glycoprotein polyamine oxidase (PAO) in different organs of the maize seedling, using affinity-purified antibodies specific for the polypeptide moiety. In the endodermal cells of the primary and lateral roots only cells with secondary walls were labeled. No labeling was observed in the intercellular spaces or on the electron dense line that represents the suberin deposition. The primary wall, laid down before the suberin layer, was unlabeled too. No labeling was found in the control sections where the primary antibodies were omitted. All the secondary walls of the xylem cells were labeled. In the mesocotyl, labeling was limited to the secondary walls of large vessel and vascular parenchyma, while the parenchymal cells were unreactive. The gold particles were limited to the secondary thickenings, in particular in the differentiating cells that were involved in secondary wall deposition, while no labeling was found over the wall of the adjacent parenchyma cells. No labeling was found over the primary wall. Only rarely were granules found over the epidermal cell walls, characterized by a helicoidal organization. The results obtained here suggest that PAO may playa crucial role in cell wall differentiation.