IMMUNODETECTION AND IMMUNOLOCALIZATION OF GLOBULIN STORAGE PROTEINS DURING ZYGOTIC AND SOMATIC EMBRYO DEVELOPMENT IN ZEA-MAYS

Globulins (GLB) are storage proteins that accumulate to high levels du ring zygotic embryo development of Zea mays L. We visualized the distr ibution of GLB during zygotic embryo development by immunolabelling of polyethylene glycol sections with a GLB-specific antiserum and a fluo rescent secondary antibody. In sections of embryos at 10 days after po llination (DAP), GLB were detected in the scutellar node only. Section s of embryos of 17 DAP showed, besides the presence of GLB in the scut ellar node, the presence of a low amount of GLB in the coleoptile and the leaf primordia. In 30-DAP embryos GLB were localized in the root, the coleorhiza, the leaf primordia, the coleoptile and in all cells of the scutellum with the exception of the epidermis and the pro-vascula r tissues. The subcellular location of GLB was visualized by immunolab elling of ultrathin sections with anti-GLB and a gold-conjugated secon dary antibody. Scutellum cells and root cortex cells of 30-DAP embryos were packed with protein storage vacuoles (PSV), which differed in el ectron density. GLB were either evenly distributed throughout the PSV or were localized in electron-dense inclusions within the PSV. SDS-PAG E and immunoblot analysis of total protein extracts indicated the pres ence of a low amount of the GLB1 processing intermediate proGLB1' in g lobular as well as mature somatic embryos. After maturation on an ABA- containing medium, somatic embryos showed the additional presence of t he next GLB1 processing intermediate GLB1'. By immune-electron microsc opy it was possible to localize GLB in globular deposits in PSV in scu tellum cells of these somatic embryos.