Intra- and extra-cellular-localization of "Cytosolic" CuZn-superoxide dismutase in spinach [Spinacia oleracea] leaf and hypocotyl
1996
Ogawa, K. (Kyoto Univ. (Japan). Faculty of Science) | Kanematsu, S. | Asada, K.
Immunogold-electron microscopic analysis of spinach leaves done with the antibody specific for "cytosolic" CuZn-superoxide dismutase (SOD) indicates that SOD is localized in the apoplast, in the nucleus and in, or near, the tonoplast. The association of CuZn-SOD with the nucleus indicates it has a role in preventing fatal mutation caused by reactive species of oxygen. The localizing site of CuZn-SOD in the apoplastic region of spinach leaf tissues corresponds to that of the accumulation of lignin. In spinach hypocotyl "cytosolic" CuZn-SOD is localized in vascular tissues where lignification and the generation of superoxide respectively were shown by the phloroglucin-HCl reaction and formation of formazane from nitroblue tetrazolium. Because hydrogen peroxide is required for lignification via the peroxidase-catalyzed reaction, the CuZn-SOD in the apoplast appears to function in the biosynthesis of lignin by causing rapid disproportionation of the superoxide anion radical prior to its interaction with cellular components and peroxidase
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