Reassessing the Roles of PIN Proteins and Anticlinal Microtubules during Pavement Cell Morphogenesis
Reassessing the Roles of PIN Proteins and Anticlinal Microtubules during Pavement Cell Morphogenesis
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DOI：
10.1104/pp.17.01554
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发表时间：
2018-01-01
期刊：
影响因子：
7.4
通讯作者：
Szymanski, Daniel B.
中科院分区：
文献类型：
--
作者：
Belteton, Samuel A.;Sawchuk, Megan G.;Szymanski, Daniel B.
叶表皮是一个生物力学外壳，影响器官的大小和形状。它的形态发生是一个多尺度的过程，在这个过程中，纳米级的细胞骨架蛋白复合体、单个细胞和细胞组形成生长模式，并定义宏观的叶片性状。相邻细胞的交指生长是一种进化保守的发育策略。了解信号通路和细胞骨架蛋白如何在这种形式的组织形态发生过程中形成细胞壁是一个重要的研究挑战。分叶细胞形态的细胞和分子控制目前被认为涉及产生亚细胞生长素梯度的PIN形成(PIN)型质膜外排载体。生长素梯度被认为是跨越细胞边界的功能，编码相邻细胞之间皮质微管和肌动蛋白细丝的稳定偏移模式。许多模型表明，沿背斜细胞壁的长寿命微管产生局部细胞壁异质性，限制了局部生长，并指定了叶形成的时间和位置。在这里，我们使用拟南芥的反向遗传学和多变量长期时间推移成像来测试当前的细胞形状控制模型。我们发现，无论是PIN蛋白还是沿背斜壁的长寿微管都不能预测肺叶形成的模式。在叶细胞的视野中，背斜微管与细胞形状无关，在细胞扩张的时间尺度上是不稳定的。我们的分析表明，背斜微管在路面细胞中具有多种功能，叶的启动可能受细胞几何形状、细胞壁应力模式和横跨背斜和斜周壁的瞬时微管网络之间的复杂相互作用控制。
The leaf epidermis is a biomechanical shell that influences the size and shape of the organ. Its morphogenesis is a multiscale process in which nanometer-scale cytoskeletal protein complexes, individual cells, and groups of cells pattern growth and define macroscopic leaf traits. Interdigitated growth of neighboring cells is an evolutionarily conserved developmental strategy. Understanding how signaling pathways and cytoskeletal proteins pattern cell walls during this form of tissue morphogenesis is an important research challenge. The cellular and molecular control of a lobed cell morphology is currently thought to involve PIN-FORMED (PIN)-type plasma membrane efflux carriers that generate subcellular auxin gradients. Auxin gradients were proposed to function across cell boundaries to encode stable offset patterns of cortical microtubules and actin filaments between adjacent cells. Many models suggest that long-lived microtubules along the anticlinal cell wall generate local cell wall heterogeneities that restrict local growth and specify the timing and location of lobe formation. Here, we used Arabidopsis (Arabidopsis thaliana) reverse genetics and multivariate long-term time-lapse imaging to test current cell shape control models. We found that neither PIN proteins nor long-lived microtubules along the anticlinal wall predict the patterns of lobe formation. In fields of lobing cells, anticlinal microtubules are not correlated with cell shape and are unstable at the time scales of cell expansion. Our analyses indicate that anticlinal microtubules have multiple functions in pavement cells and that lobe initiation is likely controlled by complex interactions among cell geometry, cell wall stress patterns, and transient microtubule networks that span the anticlinal and periclinal walls.