Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.
Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
Development. 2020 Mar 30;147(6):dev181669. doi: 10.1242/dev.181669.
Auxin is a key signal regulating plant growth and development. It is well established that auxin dynamics depend on the spatial distribution of efflux and influx carriers on the cell membranes. In this study, we employ a systems approach to characterise an alternative symplastic pathway for auxin mobilisation via plasmodesmata, which function as intercellular pores linking the cytoplasm of adjacent cells. To investigate the role of plasmodesmata in auxin patterning, we developed a multicellular model of the root tip. We tested the model predictions using the DII-VENUS auxin response reporter, comparing the predicted and observed DII-VENUS distributions using genetic and chemical perturbations designed to affect both carrier-mediated and plasmodesmatal auxin fluxes. The model revealed that carrier-mediated transport alone cannot explain the experimentally determined auxin distribution in the root tip. In contrast, a composite model that incorporates both carrier-mediated and plasmodesmatal auxin fluxes re-capitulates the root-tip auxin distribution. We found that auxin fluxes through plasmodesmata enable auxin reflux and increase total root-tip auxin. We conclude that auxin fluxes through plasmodesmata modify the auxin distribution created by efflux and influx carriers.
生长素是调节植物生长和发育的关键信号。生长素的动态依赖于细胞膜上外排和内流载体的空间分布，这一点已得到充分证实。在这项研究中，我们采用系统方法来描述通过胞间连丝进行生长素动员的替代胞质途径，胞间连丝作为连接相邻细胞细胞质的细胞间孔。为了研究胞间连丝在生长素模式形成中的作用，我们构建了根尖的多细胞模型。我们使用 DII-VENUS 生长素反应报告器来测试模型预测，通过遗传和化学干扰来比较预测和观察到的 DII-VENUS 分布，这些干扰设计用于影响载体介导和胞间连丝生长素流。该模型表明，仅载体介导的运输不能解释在根尖中测定的生长素分布。相比之下，同时包含载体介导和胞间连丝生长素流的组合模型可以再现根尖中的生长素分布。我们发现，通过胞间连丝的生长素流允许生长素回流并增加根尖的总生长素。我们得出结论，通过胞间连丝的生长素流改变了外排和内流载体产生的生长素分布。
