MAIZE POLYAMINE OXIDASE - ANTIBODY-PRODUCTION AND ULTRASOUND LOCALIZATION

In this paper we describe the ultrastructural localization of the glyc oprotein polyamine oxidase (PAO) in different organs of the maize seed ling, 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 t he 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 sectio ns where the primary antibodies were omitted. All the secondary walls of the xylem cells were labeled. In the mesocotyl, labeling was limite d to the secondary walls of large vessel and vascular parenchyma, whil e the parenchymal cells were unreactive. The gold panicles were limite d to the secondary thickenings, in particular in the differentiating c ells that were involved in secondary wall deposition, while no labelin g was found over the wall of the adjacent parenchyma cells. No labelin g was found over the primary wall. Only rarely were granules found ove r the epidermal cell walls, characterized by a helicoidal organization . The results obtained here suggest that PAO may play a crucial role i n cell wall differentiation.