Author Correction: The root meristem is shaped by brassinosteroid control of cell geometry

Growth extent and direction determine cell and whole-organ architecture. How they are spatiotemporally modulated to control size and shape? Here we tackled this question by studying the effect of brassinosteroid (BR) signaling on the structure of the root meristem. Quantification of the 3D geometry of thousands of individual meristematic cells across different tissue types showed that modulation of BR signaling yields distinct changes in growth rate and anisotropy, which affects the time cells spend in the meristem and has a strong impact on final root form. By contrast, the hormone effect on cell volume was minor, establishing cell volume as invariant to the effect of BR. Thus, BR has highest effect on cell shape and growth anisotropy, regulating overall radial growth of the meristem, while maintaining a coherent distribution of cell sizes. Moving from single-cell quantification to the whole organ, we developed a computational model of radial growth that demonstrates how differential growth regulation by BR between the inner and outer tissues shapes the meristem. The model explains the unintuitive outcomes of tissue-specific perturbation of BR signaling and suggests that the inner and outer tissues have independent but coordinated roles in growth regulation.

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The root meristem is shaped by brassinosteroid control of cell geometry

Nature Plants ◽

10.1038/s41477-021-01014-9 ◽

2021 ◽

Vol 7 (11) ◽

pp. 1475-1484

Author(s):

Y. Fridman ◽

S. Strauss ◽

G. Horev ◽

M. Ackerman-Lavert ◽

A. Reiner-Benaim ◽

...

Keyword(s):

Cell Volume ◽

Radial Growth ◽

Growth Regulation ◽

Root Meristem ◽

Three Dimensional ◽

Strong Impact ◽

Cell Geometry ◽

Cell Quantification ◽

Growth Anisotropy ◽

Hormone Effect

AbstractGrowth extent and direction determine cell and whole-organ architecture. How they are spatio-temporally modulated to control size and shape is not well known. Here we tackled this question by studying the effect of brassinosteroid (BR) signalling on the structure of the root meristem. Quantification of the three-dimensional geometry of thousands of individual meristematic cells across different tissue types showed that the modulation of BR signalling yields distinct changes in growth rate and anisotropy, which affects the time that cells spend in the meristem and has a strong impact on the final root form. By contrast, the hormone effect on cell volume was minor, establishing cell volume as invariant to the effect of BR. Thus, BR has the highest effect on cell shape and growth anisotropy, regulating the overall longitudinal and radial growth of the meristem, while maintaining a coherent distribution of cell sizes. Moving from single-cell quantification to the whole organ, we developed a computational model of radial growth. The simulation demonstrates how differential BR-regulated growth between the inner and outer tissues shapes the meristem and thus explains the non-intuitive outcomes of tissue-specific perturbation of BR signalling. The combined experimental data and simulation suggest that the inner and outer tissues have distinct but coordinated roles in growth regulation.

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Ultrastructural Changes in the Root Meristem Cells of Rubus Chamaemorus L. (Cloudberry)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100116437 ◽

1975 ◽

Vol 33 ◽

pp. 562-563

Author(s):

Arya K. Bal

Keyword(s):

Root Meristem ◽

Uranyl Acetate ◽

Particulate Material ◽

Ultrastructural Changes ◽

Cell Organelles ◽

Cytoplasmic Matrix ◽

Golgi Membranes ◽

Rubus Chamaemorus ◽

Dense Substance ◽

Ultrathin Sections

In the course of studies in the root meristem tissue of Rubus chamaemorus L. some important changes in the ultrastructural morphology were observed during the initiation of senescence at the end of the growing season.Root meristems were collected from naturally growing healthy populations of Cloudberry plants, and fixed in Karnovsky's mixture or in 2.5% glutaraldehyde in phosphate buffer. The samples were osmicated, dehydrated following usual methods and embedded in Epon. Ultrathin sections were stained in uranyl acetate and lead citrate.Figure 1 shows part of a dense cell in the meristem. The electron density of these cells is due to large amounts of a particulate material in the cytoplasmic matrix. The smallest particle seen in electron micrographs is about 40 A, although larger aggregates are also found, which remain randomly distributed in association with various cell organelles. Dense substance has been found associated with golgi membranes, proplastids, vacuoles and microtubules (Fig. 2).

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