5 research outputs found
Effect of mechanical stress on Zea root apex. I. Mechanical stress leads to the switch from closed to open meristem organization
The effect of mechanical stress on the root apical meristem (RAM) organization of Zea mays was investigated. In the experiment performed, root apices were grown through a narrowing of either circular (variant I) or elliptical (variant II) shape. This caused a mechanical impedance distributed circumferentially or from the opposite sides in variant I and II, respectively. The maximal force exerted by the growing root in response to the impedance reached the value of 0.15 N for variant I and 0.08 N for variant II. Significant morphological and anatomical changes were observed. The changes in morphology depended on the variant and concerned diminishing and/or deformation of the cross-section of the root apex, and buckling and swelling of the root. Anatomical changes, similar in both variants, concerned transformation of the meristem from closed to open, an increase in the number of the cell layers at the pole of the root proper, and atypical oblique divisions of the root cap cells. After leaving the narrowing, a return to both typical cellular organization and morphology of the apex was observed. The results are discussed in terms of three aspects: the morphological response, the RAM reorganization, and mechanical factors. Assuming that the orientation of division walls is affected by directional cues of a tensor nature, the changes mentioned may indicate that a pattern of such cues is modified when the root apex passes through the narrowing, but its primary mode is finally restored
Analysis of geometrical features of a developing lateral root by means of biophysical tools
Various scenarios of the cell pattern formation in Arabidopsis lateral root
During lateral root (LR) development a coordinate sequence of cell divisions, accompanied by a change of the organ
form takes place. Both the order of anatomical events and morphological features may vary for individual primordia. At
early stages of LR primordia development oblique division walls are inserted in cells that are symmetrically located on both
sides of the axis of the developing LR primordium, and thereby allow for the protrusion of the LR. We hypothesize that
both oblique cell wall insertion and continuous changes in primordium form could be a consequence of a local change in
stress distribution in the region of the LR initiation