SUBCELLULAR-LOCALIZATION AND TISSUE DISTRIBUTION OF POLYAMINE OXIDASE IN MAIZE (ZEA-MAYS L) SEEDLINGS

Sub-cellular localization and tissue distribution of polyamine oxidase (PAO 1.4.3.4) in maize seedlings (Zea mays L., cv.Etruria) was determined using biochemical and histochemical approaches.PAO appeared to be a sticky protein that becomes associated with each of the cell fractions to varying degrees.A relevant amount of PAO activity was found to be tightly bound to the cell wall fraction (30% and 90% of the total amount in the shoot and root, respectively).The bound activity was not released by incubation of the wall residue with high ionic-strength solution, detergents, organic solvents or EDTA.The enzyme activity was not present in freshly prepared mesophyll protoplasts, while it was recovered in the medium for protoplast preparation, suggesting that PAO was associated with cell walls.Tissue and organ distribution of PAO, investigated by a histochemical method, showed an apparent PAO localization mainly in the cell walls of the following tissues: xylem (coleoptile), xylem and xylem parenchyma (mesocotyl, root), rhizodermis, hypodermis and endodermis (root) and epidermis (coleoptile, mesocotyl).Apparent histochemical peroxidase activity showed an identical distribution.A strict spatial correlation between histochemical enzyme activity and lignosuberized depositions was observed in the cell walls of the above-mentioned tissue, except for the coleoptile epidermis and vascular parenchyma of mesocotyl and root. © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved.