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 colu mella 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 plasm alemma in the outermost layer of the columella. These apoplastic phenolic d eposits disappeared during the activation processes associated with imbibit ion and germination, but new deposits appeared successively in the nucleus, ER cisternae, protein bodies and on the outer surface of the root cap. A l arge number of phenolic deposits were observed in the outermost part of the columella, becoming less frequent towards the initial centre. Their appear ance coincided with restoration of the ER and immediately preceded cytologi cal activation. After the primary root had emerged from the seed coat, depo sits of phenolic compounds disappeared from the cytoplasm, but simultaneous ly appeared in the vacuoles. (C) 1999 Annals of Botany Company.