Deyelopmental Cells Seen withTransitions and Dynamics of the Green Fluorescent Protein Cortical ER ofArabidopsis

Arahidopsis thaliana plants were stably transformed with DNA encoding green fluorescent protein and with sequences ensuring retention in the endoplasmic reticulum (ER). Confecal laser scanning microscopy shows fluorescent ER in many cells of seedlings so a]lowing developmental changes to be documented. The arrangement of the cortical ER changes as cells mature in the hypocotyl and root epidermis. In the root, cells that have comp]eted expansion haye reticu}ate cortical ER resembling the ER described in many preyious studies. Expanding celts, however, show extensiye perforated sheets of cortica] ER which transform quite abruptly into a loose reticulum at the basipetal end of the elongation zone. The reticutum compacts in trichoblasts beginning at sites where root hairs are about