Self-organization of the vascular system in plant leaves: Inter-dependent dynamics of auxin flux and carrier proteins
Self-organization of the vascular system in plant leaves: Inter-dependent dynamics of auxin flux and carrier proteins
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DOI：
10.1016/j.jtbi.2005.03.017
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发表时间：
2005-10-21
影响因子：
2
通讯作者：
Iwasa, Y
中科院分区：
文献类型：
--
作者：
Feugier, FG;Mochizuki, A;Iwasa, Y
植物激素生长素参与整个植物维管组织的形成。跨膜载体蛋白将生长素从一个细胞运输到另一个细胞，并在每个细胞周围不对称分布，使生长素在组织中极化运动，产生生长素流，从而形成未来的维管束。根据管道化假说，细胞的生长素转运能力被认为随着生长素通量的增加而增加，导致该通量沿着生长素路径的自我增强。在这项研究中，我们在有关生长素通量形成和载体蛋白动力学的不同假设下，使用载体蛋白评估了基于运河化假设的一系列模型。模拟在具有均匀生长素产生的六方晶格上运行。位于晶格边缘的单个细胞表示叶柄，并充当生长素库。主要结果是：（1）我们获得了生长素的分支分布模式。 (2)通过响应细胞不同部分的生长素通量强度的载体蛋白调节的功能形式描述的自我增强的类型，对产生分支模式的可能性有很大影响。对于与生长素通量相比载体蛋白数量增加加速的响应函数，可能会产生分支模式。对于线性或减速响应函数，不会形成分支模式。 (3)当形成分支模式时，细胞不同部分的载体蛋白数量独立调节的情况和细胞不同部分竞争有限数量的载体蛋白的情况之间，生长素的分布有很大差异。在前一种情况下，静脉中的生长素水平低于周围组织，而在后一种情况下，静脉中的生长素含量更高。这些结果表明，渠道化是描述植物静脉图案形成的良好候选者。 (c) 2005 Elsevier Ltd. 保留所有权利。
The vegetative hormone Auxin is involved in vascular tissues formation throughout the plant. Trans-membrane carrier proteins transporting auxin from cell to cell and distributed asymmetrically around each cell give to auxin a polarized movement in tissues, creating streams of auxin that presume future vascular bundles. According to the canalization hypothesis, auxin transport ability of cells is thought to increase with auxin flux, resulting in the self-enhancement of this flux along auxin paths. In this study we evaluate a series of models based on canalization hypothesis using carrier proteins, under different assumptions concerning auxin flux formation and carrier protein dynamics. Simulations are run on a hexagonal lattice with uniform auxin production. A single cell located in the margin of the lattice indicates the petiole, and acts as an auxin sink. The main results are: (1) We obtain branching auxin distribution patterns. (2) The type of self-enhancement described by the functional form of the carrier proteins regulation responding to the auxin flux intensity in different parts of a cell, has a strong effect on the possibility of generating the branching patterns. For response functions with acceleration in the increase of carrier protein numbers compared to the auxin flux, branching patterns are likely to be generated. For linear or decelerating response functions, no branching patterns are formed. (3) When branching patterns are formed, auxin distribution greatly differs between the case in which the number of carrier proteins in different parts of a cell are regulated independently, and the case in which different parts of a cell compete for a limited number of carrier proteins. In the former case, the auxin level is lower in veins than in the surrounding tissue, while in the latter, the auxin is present in greater abundance in veins. These results suggest that canalization is a good candidate for describing plant vein pattern formation. (c) 2005 Elsevier Ltd. All rights reserved.