Morphogenesis of twisted cell wall: Chronology following an osmotic shock

Summary The effect of an osmotic shock on the subsequent growth and cell wall texture was studied at 0, 1/2, 1, 2, 4 and 24 hours. Cells were taken at the beginning of their exponential growth from mung bean hypocotyl.The shock reveals the instability and the fragility of the assembly mechanisms. It induces a rupture in the texture (formation of a loose layer) or, occasionally, the apparition of a swirling pattern. After the shock, the twisting positioning can be restored. The post-shock deposit appears similar to the pre-shock deposit. The loose layer provides a visible guide-mark (time marker) within the wall. It allows one to evaluate the oscillatory period (i.e., the duration necessary for a 180° rotation of the microfibrils). This period was found to be ca. 3 hours following a lag period of ca. 1 hour. It confirms the endogenous ultradian character of the rhythm of the assembly.