| 1. |
- Hong, Lilan, et al.
(author)
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Heterogeneity and Robustness in Plant Morphogenesis : From Cells to Organs
- 2018
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In: Annual Review of Plant Biology. - : Annual Reviews. - 1543-5008 .- 1545-2123. ; 69, s. 469-495
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Research review (peer-reviewed)abstract
- Development is remarkably reproducible, producing organs with the same size, shape, and function repeatedly from individual to individual. For example, every flower on the Antirrhinum stalk has the same snapping dragon mouth. This reproducibility has allowed taxonomists to classify plants and animals according to their morphology. Yet these reproducible organs are composed of highly variable cells. For example, neighboring cells grow at different rates in Arabidopsis leaves, sepals, and shoot apical meristems. This cellular variability occurs in normal, wild-type organisms, indicating that cellular heterogeneity (or diversity in a characteristic such as growth rate) is either actively maintained or, at a minimum, not entirely suppressed. In fact, cellular heterogeneity can contribute to producing invariant organs. Here, we focus on how plant organs are reproducibly created during development from these highly variable cells.
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| 2. |
- Meyer, Heather M, et al.
(author)
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Fluctuations of the transcription factor ATML1 generate the pattern of giant cells in the Arabidopsis sepal
- 2017
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In: eLife. - 2050-084X.
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Journal article (peer-reviewed)abstract
- Multicellular development produces patterns of specialized cell types. Yet, it is often unclear how individual cells within a field of identical cells initiate the patterning process. Using live imaging, quantitative image analyses and modeling, we show that during Arabidopsis thaliana sepal development, fluctuations in the concentration of the transcription factor ATML1 pattern a field of identical epidermal cells to differentiate into giant cells interspersed between smaller cells. We find that ATML1 is expressed in all epidermal cells. However, its level fluctuates in each of these cells. If ATML1 levels surpass a threshold during the G2 phase of the cell cycle, the cell will likely enter a state of endoreduplication and become giant. Otherwise, the cell divides. Our results demonstrate a fluctuation-driven patterning mechanism for how cell fate decisions can be initiated through a random yet tightly regulated process.
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| 3. |
- Sapala, Aleksandra, et al.
(author)
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Why plants make puzzle cells, and how their shape emerges
- 2018
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In: eLIFE. - : eLife Sciences Publications, Ltd. - 2050-084X. ; 7
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Journal article (peer-reviewed)abstract
- The shape and function of plant cells are often highly interdependent. The puzzle shaped cells that appear in the epidermis of many plants are a striking example of a complex cell shape, however their functional benefit has remained elusive. We propose that these intricate forms provide an effective strategy to reduce mechanical stress in the cell wall of the epidermis. When tissue-level growth is isotropic, we hypothesize that lobes emerge at the cellular level to prevent formation of large isodiametric cells that would bulge under the stress produced by turgor pressure. Data from various plant organs and species support the relationship between lobes and growth isotropy, which we test with mutants where growth direction is perturbed. Using simulation models we show that a mechanism actively regulating cellular stress plausibly reproduces the development of epidermal cell shape. Together, our results suggest that mechanical stress is a key driver of cell-shape morphogenesis.
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| 4. |
- Tsugawa, Satoru, et al.
(author)
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Clones of cells switch from reduction to enhancement of size variability in Arabidopsis sepals
- 2017
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In: Development. - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 144:23, s. 4398-4405
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Journal article (peer-reviewed)abstract
- Organs form with remarkably consistent sizes and shapes during development, whereas a high variability in growth is observed at the cell level. Given this contrast, it is unclear how such consistency in organ scale can emerge from cellular behavior. Here, we examine an intermediate scale, the growth of clones of cells in Arabidopsis sepals. Each clone consists of the progeny of a single progenitor cell. At early stages, we find that clones derived from a small progenitor cell grow faster than those derived from a large progenitor cell. This results in a reduction in clone size variability, a phenomenon we refer to as size uniformization. By contrast, at later stages of clone growth, clones change their growth pattern to enhance size variability, when clones derived from larger progenitor cells grow faster than those derived from smaller progenitor cells. Finally, we find that, at early stages, fast growing clones exhibit greater cell growth heterogeneity. Thus, cellular variability in growth might contribute to a decrease in the variability of clones throughout the sepal.
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| 5. |
- Zhu, Mingyuan, et al.
(author)
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Robust organ size requires robust timing of initiation orchestrated by focused auxin and cytokinin signalling
- 2020
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In: Nature Plants. - : Springer Science and Business Media LLC. - 2055-0278. ; 6, s. 686-698
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Journal article (peer-reviewed)abstract
- The shape of plant organs shows low variability. Sepals of the same age look the same. Here the authors identify one transcription factor (DRMY1) crucial for sepal size reproducibility, and its effect on initiation timing and growth of the organ. Organ size and shape are precisely regulated to ensure proper function. The four sepals in each Arabidopsis thaliana flower must maintain the same size throughout their growth to continuously enclose and protect the developing bud. Here we show that DEVELOPMENT RELATED MYB-LIKE 1 (DRMY1) is required for both timing of organ initiation and proper growth, leading to robust sepal size in Arabidopsis. Within each drmy1 flower, the initiation of some sepals is variably delayed. Late-initiating sepals in drmy1 mutants remain smaller throughout development, resulting in variability in sepal size. DRMY1 focuses the spatiotemporal signalling patterns of the plant hormones auxin and cytokinin, which jointly control the timing of sepal initiation. Our findings demonstrate that timing of organ initiation, together with growth and maturation, contribute to robust organ size.
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