REARRANGEMENTS OF F-ACTIN DURING STOMATOGENESIS VISUALIZED BY CONFOCAL MICROSCOPY IN FIXED AND PERMEABILIZED TRADESCANTIA LEAF EPIDERMIS

New details of F-actin organisation in leaf epidermal and stomatal cel ls were revealed by rhodamine - and fluorescein - phalloidin staining of fixed epidermal peels of Tradescantia virginiana and visualisation by confocal microscopy. Non-specialised epidermal cells contain highly organised arrays of fine cortical actin filaments aligned in transver se or oblique orientations. In interphase guard mother cells (GMCs), t he arrangement of cortical F-actin changes on the periclinal and antic linal cell walls at different times during differentiation. Initially, cortical F-actin on the periclinal surfaces is oriented transversely and F-actin is evenly distributed around the anticlinal walls. Followi ng polarisation of the adjacent subsidiary mother cells (SMCs), actin in GMCs concentrates on the lateral anticlinal walls, but not on the t ransverse walls. Subsequently, F-actin on the periclinal walls reorien ts to radial and then longitudinal. Organisation of F-actin in SMCs ap pears to be influenced by the adjacent GMCs and coordination in F-acti n arrangements in cells of the stomatal complex continues through to t he formation of the guard cell pair. Our studies indicate that actin b ands marking the division site in prophase cells, and detected in micr oinjected living material, are a particularly labile subset of F-actin . Actin bands were difficult to preserve, even when aldehyde fixation was avoided, in contrast to all interphase and mitotic F-actin.