Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, 97082, Würzburg, Germany.
College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.
Nat Commun. 2018 Mar 21;9(1):1174. doi: 10.1038/s41467-018-03582-5.
Auxin is a key regulator of plant growth and development, but the causal relationship between hormone transport and root responses remains unresolved. Here we describe auxin uptake, together with early steps in signaling, in Arabidopsis root hairs. Using intracellular microelectrodes we show membrane depolarization, in response to IAA in a concentration- and pH-dependent manner. This depolarization is strongly impaired in aux1 mutants, indicating that AUX1 is the major transporter for auxin uptake in root hairs. Local intracellular auxin application triggers Ca signals that propagate as long-distance waves between root cells and modulate their auxin responses. AUX1-mediated IAA transport, as well as IAA triggered calcium signals, are blocked by treatment with the SCF - inhibitor auxinole. Further, they are strongly reduced in the tir1afb2afb3 and the cngc14 mutant. Our study reveals that the AUX1 transporter, the SCF receptor and the CNGC14 Ca channel, mediate fast auxin signaling in roots.
生长素是植物生长和发育的关键调节剂，但激素运输和根响应之间的因果关系仍未解决。在这里，我们描述了拟南芥根毛中的生长素摄取以及信号转导的早期步骤。我们使用细胞内微电极显示，在浓度和 pH 值依赖性的方式下，对 IAA 的响应会发生膜去极化。在 aux1 突变体中，这种去极化受到强烈抑制，表明 AUX1 是根毛中生长素摄取的主要转运蛋白。局部细胞内生长素应用会引发 Ca 信号，这些信号在根细胞之间作为长距离波传播，并调节它们的生长素响应。AUX1 介导的 IAA 运输以及 IAA 触发的钙信号被 SCF - 抑制剂 auxinole 处理所阻断。此外，它们在 tir1afb2afb3 和 cngc14 突变体中也明显减少。我们的研究表明，AUX1 转运蛋白、SCF 受体和 CNGC14 Ca 通道介导了根中的快速生长素信号转导。
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