Actin Reorganization Triggers Rapid Cell Elongation in Roots
Actin Reorganization Triggers Rapid Cell Elongation in Roots
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DOI：
10.1104/pp.18.00557
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发表时间：
2018-11-01
期刊：
影响因子：
7.4
通讯作者：
Umeda, Masaaki
中科院分区：
文献类型：
--
作者：
Takatsuka, Hirotomo;Higaki, Takumi;Umeda, Masaaki
根的生长受细胞分裂和细胞伸长的机制控制，这些机制对各种内部和外部因素做出反应。在拟南芥中，近端分生组织(PM)产生的细胞在过渡区(TZ)和伸长/分化区(EDZ)伸长分化。以前的研究已经证明，内复制与根细胞的伸长有关；然而，细胞长度增加超过2倍的方式仍不清楚。在这里，我们发现拟南芥根的表皮和皮层细胞经历了两种快速细胞伸长模式：第一种快速细胞伸长发生在近端分生组织和TZ的交界处，第二种模式发生在从TZ向EDZ的转变过程中。我们先前的研究表明，细胞分裂素信号促进内复制，这触发了第一次快速的细胞伸长。我们的细胞学和遗传学数据显示，第二次快速细胞伸长包括独立于内复制的动态肌动蛋白重组。细胞分裂素通过激活细胞分裂素受体拟南芥组氨酸KINASE 3(AHK3)和AHK4以及B型转录因子拟南芥反应REGULATOR2的信号通路来促进肌动蛋白捆绑和由此产生的第二次快速细胞伸长。我们的结果表明，细胞分裂素通过控制不同的细胞事件促进两种模式的快速细胞伸长：内复制和肌动蛋白重组。
Root growth is controlled by mechanisms underlying cell division and cell elongation, which respond to various internal and external factors. In Arabidopsis (Arabidopsis thaliana), cells produced in the proximal meristem (PM) elongate and differentiate in the transition zone (TZ) and the elongation/differentiation one (EDZ). Previous studies have demonstrated that endoreplication is involved in root cell elongation; however, the manner by which cells increase in length by more than 2-fold remains unknown. Here, we show that epidermal and cortical cells in Arabidopsis roots undergo two modes of rapid cell elongation: the first rapid cell elongation occurs at the border of the proximal meristem and the TZ, and the second mode occurs during the transition from the TZ to the EDZ. Our previous study showed that cytokinin signaling promotes endoreplication, which triggers the first rapid cell elongation. Our cytological and genetic data revealed that the second rapid cell elongation involves dynamic actin reorganization independent of endoreplication. Cytokinins promote actin bundling and the resultant second rapid cell elongation through activating the signaling pathway involving the cytokinin receptors ARABIDOPSIS HISTIDINE KINASE3 (AHK3) and AHK4 and the B-type transcription factor ARABIDOPSIS RESPONSE REGULATOR2. Our results suggest that cytokinins promote the two modes of rapid cell elongation by controlling distinct cellular events: endoreplication and actin reorganization.