Differential growth regulation in plants

植物激素生长素在不对称生长调控中具有重要作用，最终控制植物的结构。然而，人们对植物生长调控知之甚少。迄今为止，对植物激素串扰对细胞生长调节的系统分析尚缺乏。在这里，我们建议使用根表皮细胞作为模型系统来系统地解决生长素调节的细胞分裂，伸长和分化事件。根表皮细胞在根毛细胞（毛原细胞）和非毛细胞（无毛原细胞）中有规律地分布。毛原细胞和无毛原细胞之间的第一个明显差异已经在分生组织区域被检测到，在那里毛原细胞显示出更强烈的细胞质染色，更短的细胞经历更高的细胞分裂率，相对于细胞伸长，空泡化延迟。除了不同的生长行为外，根表皮细胞还可以用于超分辨率成像技术，并且在根-土壤界面形成，根器官大小确定和向地生长响应中具有突出的发育重要性。因此，毛原细胞/无毛原细胞规格代表了细胞大小调节的适用模型。我们建议使用表皮根细胞作为一个合适的模型系统来揭示生长素依赖性的差异生长调节。值得注意的是，在生长素处理下，仅显示毛细胞或仅显示无壁细胞发育的根毛信号突变体分别表现出过敏和抗性的根生长。我们将特别关注生长素对液泡生物发生的依赖调节及其在肿胀驱动的细胞扩增中的重要性。这种系统的方法，利用遗传、药理学、转录和定义的活细胞成像工具，将为植物细胞生长的特异性调节提供新的见解。

The phytohormone auxin has outstanding importance for asymmetric growth regulation, ultimately controlling plant architecture. However, plant growth regulation is poorly understood. To date, systematic analysis of phytohormonal crosstalk for cellular growth regulation is missing.Here we propose to use root epidermal cells as a model system to systematically address auxin regulated cellular division, elongation and differentiation events. Root epidermal cells are regularly spaced in root hair (trichoblast) and non-hair (atrichoblast) cells. The first visible differences between tricho- and atrichoblast cells are already detectable in the meristematic region, where trichoblast cells show a more intense cytoplasmic staining, shorter cells that undergo a higher rate of cell division, and a delay in vacuolization relative to cell elongation. Beside the differential growth behavior, root epidermal cells are accessible for super resolution imaging techniques and moreover have outstanding developmental importance for root-soil interface formation, root organ size determination and gravitropic growth responses. Hence, trichoblast/atrichoblast specification represents an applicable model for cell size regulation. We propose to use epidermal root cells as a suitable model system to unravel auxin dependent differential growth regulation. Notably, root hair signaling mutants displaying either only tricho- or only atrichoblast development show hypersensitive and resistant root growth when treated with auxin, respectively. We will particularly focus on the auxin-dependent regulation of vacuolar biogenesis and its importance in turgor driven cell expansion. This systematic approach, using genetic, pharmacological, transcriptom and defined live cell imaging tools, will provide novel insight into plant specific regulation of cellular growth.