LIQUID-CRYSTAL ORDER AND TURBULENCE IN THE PLANAR TWIST OF THE GROWING PLANT-CELL WALLS

During growth, the plant cell wall behaves as a dynamic structure that exemplifies a case of unstable balance between a capability to organize a characteristic order and a permanent tendency to destroy the order. This interpretation allows previous results to be complemented and reappraised; it also integrates the cell wall behavior into a unified frame. The wall thickenings are structured according to a crystal-like pattern (cholesteric mesophase). Laminar helicoids are locally deposited on cell facets and form actual flat and planar twists in which the causes of topological defects are minimized. The helicoidal pattern is short-lived and its occurrence results from a complex interplay between self-assembly and disassembly properties. Two alternative processes destroy this critical state: 1. Externally, the surface extension which produces a progressive degradation and a randomization by shearing and stretching; 2. Internally, aleatory and punctual instabilities which alter the genesis of the system at the plasmalemma/wall interface. As the time goes on, the twisting either resumes or, in contrast, the perturbation increases. The system tends to become unpredictable thus suggesting turbulence.