Supplemental material for “Three-Dimensional Analysis of Synctial-Type Cell Plates during Endosperm Cellularization Visualized by High Resolution Tomography”

 

M.S. Otegui, D.N. Mastonarde, B.-H. Kang, S.Y. Bednarek, L.A. Staehelin

 

Video sequence 1. Illustration of the Tomographic Modeling Process.Video 1

The first segment of this movie shows a sequence of 2.3nm thick tomographic slices throughout a tomographic reconstructed volume. The second, depicts the same slices with the colored contours that have been traced around the different organelles: cell plates (yellow), microtubules (magenta), non-coated vesicles (light green), clathrin-coated vesicles (red), and endosplasmic reticulum (dark green).

 

Video sequence 2. Tomographic Reconstruction of a Wide Tubular Network (tomographic volume: 2.8 x 2.8 x 0.25 mm³).Video 2

Note the distribution of the mini-phragmoplast (magenta), non-coated vesicles (light green), and hourglass-shaped intermediates (green) around the cell plate (yellow). A mini-phragmoplast in the right upper corner (initial position in the movie sequence) is initiating a new cell plate assembly site. Dynamin-like rings (blue) constrict the tubules at irregular intervals. A multivesicular body (white) is seen in close proximity to the cell plate. Clathrin coats and clathrin-coated vesicles are depicted in red.

 

Video sequence 3. Tomographic Reconstruction of a Syncytial-Type Cell Plate (tomographic volume: 1.4 x 4.2 x 0.25 mm³).Video 3

The central domain of this cell plate corresponds to the convoluted fenestrated sheet stage. Note the complex architecture of this membranous cell plate intermediate. Numerous clathrin-coated buds (red) are budding off from the convoluted sheets. On the left side of this cell plate, which corresponds to a growing edge, some wide tubules are seen extending towards the tonoplast membrane (light blue). Two dynamin-like rings (blue) are constricting these tubules. Non-coated vesicles (light green), microtubules (magenta).

 

Video sequence 4. Tomographic Reconstruction of the Junctional Area Where Three Cell Plates Are Fusing Together (tomographic volume: 2.8 x 2.8 x 0.5 mm³).Video 4

The three cell plates are at different stages of development. The youngest one is associated with the highest concentration of microtubules (magenta) and non-coated vesicles (light green). Only the cell plates, microtubules, vesicles and Golgi stacks are depicted in this movie to highlight the cell-plate growing sites and the complexity of the membranous intermediates during cell plate assembly.

 

Video sequence 5.Video 5

Same Tomographic Model of the Junctional Area with Surrounding Organelles. In the vicinity of these three cell plates there are three mitochondria (violet), endoplasmic reticulum cisternae (dark green), a peroxisome (reddish purple), a Golgi stack (turquoise), the tonoplast membrane of a vacuole (blue), a multivesicular body (white), and more than 20,000 thousands ribosomes (gray).