Topological traits of a cellular pattern versus growth rate anisotropy in radish roots

Abstract

The topology of a cellular pattern, which means the spatial arrangement of cells, directly corresponds with cell packing, which is crucial for tissue and organ functioning. The topological features of cells that are typically analyzed are the number of their neighbors and the cell area. To date, the objects of most topological studies have been the growing cells of the surface tissues of plant and animal organs. Some of these researches also provide verification of Lewis’s Law concerning the linear correlation between the number of neighboring cells and the cell area. Our aim was to analyze the cellular topology and applicability of Lewis’s Law to an anisotropically growing plant organ. The object of our study was the root apex of radish. Based on the tensor description of plant organ growth, we specified the level of anisotropy in specific zones (the root proper, the columella of the cap and the lateral parts of the cap) and in specific types of both external (epidermis) and internal tissues (stele and ground tissue) of the apex. The strongest anisotropy occurred in the root proper, while both zones of the cap showed an intermediate level of anisotropy of growth. Some differences in the topology of the cellular pattern in the zones were also detected; in the root proper, six-sided cells predominated, while in the root cap columella and in the lateral parts of the cap, most cells had five neighbors. The correlation coefficient r L between the number of neighboring cells and the cell area was high in the apex as a whole as well as in all of the zones except the root proper and in all of the tissue types except the ground tissue. In general, Lewis’s Law was fulfilled in the anisotropically growing radish root apex. However, the level of the applicability ( r L value) of Lewis’s Law was negatively correlated with the level of the anisotropy of growth, which may suggest that in plant organs in the regions of anisotropic growth, the number of neighboring cells is less dependent on the cell size. Electronic supplementary material The online version of this article (10.1007/s00709-019-01362-6) contains supplementary material, which is available to authorized users.

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“…The volume of intercellular spaces, sphericity of voids, and percent porosity were comparatively higher in LR than the crown roots, indicating a more intricate and highly connected air space network ( Supplementary Table S5 ) [ 28–30 ]. Anisotropy, which affects morphogenesis of plant organs [ 31 ], had values that were higher for the crown roots compared to LR, indicating higher morphogenesis in crown roots [ 32 ]. The void shape factor values of crown roots were found to be higher than those of LR (Table S5) and may have a correlation with the correspondingly high anisotropy values [ 33 ].…”

Whole-Tissue Three-Dimensional Imaging of Rice at Single-Cell Resolution

“…Topology and anisotropy are crucial characteristics to understand the development of organs with complex cellular patterns [ 4 ]. The relationship between the topology of cells and anisotropy of tissues in plants has been investigated [ 5 ]. Mechanical stress in the cell wall is caused by the 3D arrangement of cells, which is essential for proper organ differentiation [ 6 ].…”