An Auxin Gradient and Maximum in the Arabidopsis Root Apex Shown by High-Resolution Cell-Specific Analysis of IAA Distribution and Synthesis
An Auxin Gradient and Maximum in the Arabidopsis Root Apex Shown by High-Resolution Cell-Specific Analysis of IAA Distribution and Synthesis
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DOI：
10.1105/tpc.109.066480
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发表时间：
2009-06-01
期刊：
影响因子：
11.6
通讯作者：
Ljung, Karin
中科院分区：
文献类型：
--
作者：
Petersson, Sara V.;Johansson, Annika I.;Ljung, Karin
植物生长调节剂生长素（吲哚-3-乙酸[IAA]）的局部浓度梯度被认为指导器官原基和干细胞壁龛的定位，并指导细胞的分裂、扩增和分化。支持梯度假设的内源性IAA浓度的高分辨率测量需要证实这一假设。在这里，我们介绍了绿色荧光蛋白标记的细胞类型的荧光激活细胞分选结合高灵敏度的质谱方法作为分析IAA分布和代谢在细胞分辨率的新手段。结果表明，IAA浓度梯度在拟南芥根尖内存在，在根尖的组织静止中心有明显的最大值。我们还证明了根尖是IAA的重要来源，所有类型的细胞都表现出很高的合成能力，这表明根尖的局部生物合成对生长素的稳态有很大的贡献。我们的研究结果表明，局部生物合成和极性运输共同作用，在根尖产生生长素梯度和最大值。
Local concentration gradients of the plant growth regulator auxin (indole-3-acetic acid [IAA]) are thought to instruct the positioning of organ primordia and stem cell niches and to direct cell division, expansion, and differentiation. High-resolution measurements of endogenous IAA concentrations in support of the gradient hypothesis are required to substantiate this hypothesis. Here, we introduce fluorescence-activated cell sorting of green fluorescent protein-marked cell types combined with highly sensitive mass spectrometry methods as a novel means for analyses of IAA distribution and metabolism at cellular resolution. Our results reveal the presence of IAA concentration gradients within the Arabidopsis thaliana root tip with a distinct maximum in the organizing quiescent center of the root apex. We also demonstrate that the root apex provides an important source of IAA and that cells of all types display a high synthesis capacity, suggesting a substantial contribution of local biosynthesis to auxin homeostasis in the root tip. Our results indicate that local biosynthesis and polar transport combine to produce auxin gradients and maxima in the root tip.