The Ectomycorrhizal Fungus Laccaria bicolor Stimulates Lateral Root Formation in Poplar and Arabidopsis through Auxin Transport and Signaling
The Ectomycorrhizal Fungus Laccaria bicolor Stimulates Lateral Root Formation in Poplar and Arabidopsis through Auxin Transport and Signaling
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DOI：
10.1104/pp.109.147231
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发表时间：
2009-12-01
期刊：
影响因子：
7.4
通讯作者：
Legue, Valerie
中科院分区：
文献类型：
--
作者：
Felten, Judith;Kohler, Annegret;Legue, Valerie
树根和外生菌根真菌相互作用的早期阶段，在共生建立之前，伴随着侧根(LR)发育的刺激。本研究旨在从生长素运输和信号转导途径两个方面，寻找调控白杨和毛白杨外生菌根真菌Laccaria biolor早期信号交换过程中LR发育的基因网络。我们的数据表明，杨树和拟南芥与双色拟南芥相互作用后LR发育的增加并不依赖于植物形成外生菌根的能力。LR刺激与根尖生长素积累的增加是平行的。用1-萘基邻苯二甲酸阻断植物生长素的极性运输抑制了LR的发育和生长素的积累。基于寡阵列的转录谱分析表明，杨树根系在双色乳杆菌释放的分子作用下有2,945个基因的差异表达，其中包括生长素极性运输的几个组成部分(PtaPIN和PtaAUX基因)、生长素结合(PtaGH3基因)和生长素信号转导(PtaIAA基因)。PtaPIN9的转录本、拟南芥AtPIN2的同源物和几个PtaIAA的转录本在早期相互作用阶段特异积累。这些快速诱导基因的表达被1-萘基邻苯二甲酸抑制。因此，在这些基因同源缺失的拟南芥转基因植株中，与双色拟南芥接触时的LR刺激减少或消失。此外，在拟南芥Pin2中，根尖生长素在与真菌接触时增加了。我们提出了一个模型，在该模型中，真菌诱导的生长素在根尖积累，通过PtaPIN9依赖的生长素重新分配和基于PtaIAA的生长素信号转导机制来刺激LR的形成。
The early phase of the interaction between tree roots and ectomycorrhizal fungi, prior to symbiosis establishment, is accompanied by a stimulation of lateral root (LR) development. We aimed to identify gene networks that regulate LR development during the early signal exchanges between poplar (Populus tremula x Populus alba) and the ectomycorrhizal fungus Laccaria bicolor with a focus on auxin transport and signaling pathways. Our data demonstrated that increased LR development in poplar and Arabidopsis (Arabidopsis thaliana) interacting with L. bicolor is not dependent on the ability of the plant to form ectomycorrhizae. LR stimulation paralleled an increase in auxin accumulation at root apices. Blocking plant polar auxin transport with 1-naphthylphthalamic acid inhibited LR development and auxin accumulation. An oligoarray-based transcript profile of poplar roots exposed to molecules released by L. bicolor revealed the differential expression of 2,945 genes, including several components of polar auxin transport (PtaPIN and PtaAUX genes), auxin conjugation (PtaGH3 genes), and auxin signaling (PtaIAA genes). Transcripts of PtaPIN9, the homolog of Arabidopsis AtPIN2, and several PtaIAAs accumulated specifically during the early interaction phase. Expression of these rapidly induced genes was repressed by 1-naphthylphthalamic acid. Accordingly, LR stimulation upon contact with L. bicolor in Arabidopsis transgenic plants defective in homologs of these genes was decreased or absent. Furthermore, in Arabidopsis pin2, the root apical auxin increase during contact with the fungus was modified. We propose a model in which fungus-induced auxin accumulation at the root apex stimulates LR formation through a mechanism involving PtaPIN9-dependent auxin redistribution together with PtaIAA-based auxin signaling.