Meents Anja K, Furch Alexandra C U, Almeida-Trapp Marília, Özyürek Sedef, Scholz Sandra S, Kirbis Alexander, Lenser Teresa, Theißen Günter, Grabe Veit, Hansson Bill, Mithöfer Axel, Oelmüller Ralf
Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany.
Department of Plant Physiology, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany.
Front Microbiol. 2019 Mar 12;10:380. doi: 10.3389/fmicb.2019.00380. eCollection 2019.
Auxin (indole-3-acetic acid, IAA) is an important phytohormone involved in root growth and development. Root-interacting beneficial and pathogenic fungi utilize auxin and its target genes to manipulate the performance of their hosts for their own needs. In order to follow and visualize auxin effects in fungi-colonized Arabidopsis roots, we used the dual auxin reporter construct :::: and fluorescence microscopy as well as LC-MS-based phytohormone analyses. We demonstrate that the beneficial endophytic fungi and produce and accumulate IAA in their mycelia, in contrast to the phytopathogenic biotrophic fungus and the necrotrophic fungus . Within 3 h after exposure of Arabidopsis roots to the pathogens, the signals of the auxin-responsive reporter genes disappeared. When exposed to , significantly higher auxin levels and stimulated expression of auxin-responsive reporter genes were detected both in lateral root primordia and the root elongation zone within 1 day. Elevated auxin levels were also present in the /Arabidopsis root interaction, but no downstream effects on auxin-responsive reporter genes were observed. However, the jasmonate level was strongly increased in the colonized roots. We propose that the lack of stimulated root growth upon infection with is not caused by the absence of auxin, but an inhibitory effect mediated by high jasmonate content.
生长素（吲哚 - 3 - 乙酸，IAA）是一种参与根生长和发育的重要植物激素。与根相互作用的有益真菌和致病真菌利用生长素及其靶基因来根据自身需求操纵宿主的表现。为了追踪并可视化生长素在真菌定殖的拟南芥根中的作用，我们使用了双生长素报告基因构建体以及荧光显微镜和基于液相色谱 - 质谱联用的植物激素分析方法。我们证明，与植物致病性活体营养真菌和死体营养真菌相比，有益内生真菌在其菌丝体中产生并积累IAA。在拟南芥根暴露于病原体后3小时内，生长素响应报告基因的信号消失。当暴露于[具体真菌名称未给出]时，在1天内，侧根原基和根伸长区均检测到显著更高的生长素水平以及生长素响应报告基因的表达受到刺激。在[具体真菌名称未给出]/拟南芥根相互作用中也存在生长素水平升高的情况，但未观察到对生长素响应报告基因的下游影响。然而，在定殖的根中茉莉酸水平大幅升高。我们提出，感染[具体真菌名称未给出]后根生长未受刺激并非由于生长素缺乏，而是高茉莉酸含量介导的抑制作用。
