Cytochemical Localization of Phenolic Compounds in Columella Cells of the Root Cap in Seeds of Brassica napus—Changes in the Localization of Phenolic Compounds during Germination

Changes in the localization of phenolic compounds were investigated in columella cells of embryonic roots in 1-year-old Brassica napus seeds during 48 h of imbibition and germination. In dry, dormant seeds, phenolic compounds were located in the apoplastic compartment between the cell wall and plasmalemma in the outermost layer of the columella. These apoplastic phenolic deposits disappeared during the activation processes associated with imbibition and germination, but new deposits appeared successively in the nucleus, ER cisternae, protein bodies and on the outer surface of the root cap. A large number of phenolic deposits were observed in the outermost part of the columella, becoming less frequent towards the initial centre. Their appearance coincided with restoration of the ER and immediately preceded cytological activation. After the primary root had emerged from the seed coat, deposits of phenolic compounds disappeared from the cytoplasm, but simultaneously appeared in the vacuoles.