Model-Based Analysis of Arabidopsis Leaf Epidermal Cells Reveals Distinct Division and Expansion Patterns for Pavement and Guard Cells
Model-Based Analysis of Arabidopsis Leaf Epidermal Cells Reveals Distinct Division and Expansion Patterns for Pavement and Guard Cells
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DOI：
10.1104/pp.111.181180
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发表时间：
2011-08-01
期刊：
影响因子：
7.4
通讯作者：
De Veylder, Lieven
中科院分区：
文献类型：
--
作者：
Asl, Leila Kheibarshekan;Dhondt, Stijn;De Veylder, Lieven
为了有效地捕捉阳光进行光合作用，叶子通常会发育成扁平而薄的结构。这种发展是由细胞分裂和扩张驱动的，但这些过程的个体贡献目前尚不清楚，主要是因为在发育中的器官中，由于它们的紧密连接，在实验中很难解开它们。为了解决这个问题，我们建立了一个数学模型来描述单个表皮细胞可能的分裂模式和扩张率。该模型用于拟南芥（Arabidopsis thaliana）第一个叶片对发育过程中在1 d时间间隔内获得的细胞数量和大小的实验数据。这些参数是通过无导数优化方法获得的，该方法最大限度地减少了预测和实验观察到的细胞大小分布之间的差异。该模型允许我们计算细胞分裂为保护细胞或铺路细胞的概率，它可以分裂的最大大小，以及在叶片发育过程中每个点的平均细胞分裂和扩张率。令人惊讶的是，平均细胞周期持续时间在整个叶片发育过程中保持不变，而没有证据表明路面细胞分裂的最大细胞大小阈值。此外，该模型预测表皮内不同大小的相邻细胞以明显不同的相对速率扩张，这可以通过直接观察得到验证。我们得出的结论是，细胞分裂似乎独立于细胞扩增的状态而发生，而细胞周期可能是一个计时器，而不是一个大小调节的机器。
To efficiently capture sunlight for photosynthesis, leaves typically develop into a flat and thin structure. This development is driven by cell division and expansion, but the individual contribution of these processes is currently unknown, mainly because of the experimental difficulties to disentangle them in a developing organ, due to their tight interconnection. To circumvent this problem, we built a mathematic model that describes the possible division patterns and expansion rates for individual epidermal cells. This model was used to fit experimental data on cell numbers and sizes obtained over time intervals of 1 d throughout the development of the first leaf pair of Arabidopsis (Arabidopsis thaliana). The parameters were obtained by a derivative-free optimization method that minimizes the differences between the predicted and experimentally observed cell size distributions. The model allowed us to calculate probabilities for a cell to divide into guard or pavement cells, the maximum size at which it can divide, and its average cell division and expansion rates at each point during the leaf developmental process. Surprisingly, average cell cycle duration remained constant throughout leaf development, whereas no evidence for a maximum cell size threshold for cell division of pavement cells was found. Furthermore, the model predicted that neighboring cells of different sizes within the epidermis expand at distinctly different relative rates, which could be verified by direct observations. We conclude that cell division seems to occur independently from the status of cell expansion, whereas the cell cycle might act as a timer rather than as a size-regulated machinery.