WINDING THREADS AROUND PLANT-CELLS - APPLICATIONS OF THE GEOMETRICAL MODEL FOR MICROFIBRIL DEPOSITION

Based on precise information about the orientations of cellulose micro fibrils (CMFs) in the secondary cell wall of the Equisetum hyemale roo t hair, a geometrical model was recently put forward to account for th e deposition orientation of CMFs. The model supposes that synthases sp in out the CMFs and that geometrical laws dictate their movement. Taki ng space-limiting conditions into account, CMF orientation is dependen t on cell morphology, the amount of other wall molecules adhering to t he CMFs, and the number and distribution pattern of synthases. In the present paper this geometrical model for CMF deposition is further app lied to non-tip-growing angular cells with varying diameters, cells wi th tapering morphology, various distribution patterns of synthases, va rious matrix/fibril ratios, and intercalarily elongating cells. The mo del can accurately predict the actual wall textures in a great variety of cell walls. In the proposed model for CMF orientation, microtubule s are not required as cellular guiding structures for the CMFs, not ev en in elongating walls. They are supposed to be involved in cell elong ation, possibly by delivering wall material including CMF synthases.