Movie S2.

Lateral photobleaching experiments display the bidirectional movement of GFP-CESA3 particles during PCW synthesis and the directionally coherent movement of GFP-CESA7 particles during SCW synthesis. Time-lapse imaging was conducted for 2 min before photobleaching the lateral edges of the cells. In PCW-synthesizing nontransdifferentiated (NT) seedlings, GFP-CESA3 particles on a shared track move equally into the right and left bleached areas during PCW synthesis. In contrast, GFP-CESA7 particles on a shared track move either into the left or right bleached area during SCW synthesis both before (BHF) and during (DHF) hoop formation. Oryzalin treatment (BHF + ORY) did not disrupt the directionally coherent movement of GFP-CESA7 particles during SCW synthesis. The frame rate is 15 frames per second. (Scale bar: 10 μm.)