Auxin-mediated Aux/IAA-ARF-HB signaling cascade regulates secondary xylem development in Populus
Auxin-mediated Aux/IAA-ARF-HB signaling cascade regulates secondary xylem development in Populus
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生长素介导的 Aux/IAA-ARF-HB 信号级联调节杨属次生木质部发育
DOI：
10.1111/nph.15658
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发表时间：
2019
期刊：
影响因子：
9.4
通讯作者：
Luo Keming
中科院分区：
文献类型：
--
作者：
Xu Changzheng;Shen Yun;He Fu;Fu Xiaokang;Yu Hong;Lu Wanxiang;Li Yongli;Li Chaofeng;Fan Di;Wang Hua Cassan;Luo Keming
木材的生长发育受多种植物激素的严格调控，而生长素在这一过程中起着重要的调节作用。在此，我们鉴定了毛白杨（Populus tomentosa）中的一个Aux/Indole-3-Acetic Acid 9（IAA 9）-Auxin Response Factor 5（ARF 5）模块，它是控制早期木质部发育的生长素信号传导的关键介质。主要在维管形成层和发育中的次生木质部中表达，并受外源生长素诱导。PtoIAA 9基因在转基因白杨中的过量表达显著抑制了次生木质部的发育。我们进一步表明PtoIAA 9通过C末端III/IV结构域与PtoARF 5同源物相互作用。没有III/IV结构域的截短PtoARF5.1蛋白拯救了由PtoIAA 9 m引起的缺陷表型。表达分析表明，PtoIAA 9-PtoARF 5模块调节PtoIAA 9 m-和PtoARF 5.1-过表达植物中与次生维管发育相关的基因的表达。此外，PtoARF5.1还能与两个III类同源结构域-亮氨酸拉链（HD‐ZIP III）基因PtoHB 7和PtoHB 8的启动子结合，调控次生木质部的形成，这表明Aux/IAA 9 ‐ ARF 5模块是生长素信号传导所必需的，通过协调HD‐ZIP III转录因子的表达来调控杨树木材的形成。
Wood development is strictly regulated by various phytohormones and auxin plays a central regulatory role in this process. However, how the auxin signaling is transducted in developing secondary xylem during wood formation in tree species remains unclear.Here, we identified an Aux/INDOLE‐3‐ACETIC ACID 9 (IAA9)‐AUXIN RESPONSE FACTOR 5 (ARF5) module inPopulus tomentosaas a key mediator of auxin signaling to control early developing xylem development.PtoIAA9, a canonicalAux/IAAgene, is predominantly expressed in vascular cambium and developing secondary xylem and induced by exogenous auxin. Overexpression ofPtoIAA9mencoding a stabilized IAA9 protein significantly represses secondary xylem development in transgenic poplar. We further showed that PtoIAA9 interacts with PtoARF5 homologs via the C‐terminal III/IV domains. The truncated PtoARF5.1 protein without the III/IV domains rescued defective phenotypes caused byPtoIAA9m. Expression analysis showed that the PtoIAA9‐PtoARF5 module regulated the expression of genes associated with secondary vascular development inPtoIAA9m‐ andPtoARF5.1‐overexpressing plants. Furthermore, PtoARF5.1 could bind to the promoters of two Class III homeodomain‐leucine zipper (HD‐ZIP III) genes,PtoHB7andPtoHB8, to modulate secondary xylem formation.Taken together, our results suggest that the Aux/IAA9‐ARF5 module is required for auxin signaling to regulate wood formation via orchestrating the expression of HD‐ZIP III transcription factors in poplar.