MicroRNA- and transcription factor profiling: analyzing two regulatory steps of plant cell reprogramming in response to arbuscular mycorrhizal (AM) colonization

在丛枝菌根（AM）共生过程中，导致植物细胞快速而深刻的重编程的机制在很大程度上是未知的。拟议的项目将分析植物细胞调控网络的两个主要水平，以确定它们参与对AM定植的反应：转录因子（TF）和microRNA（miRNA）。在植物中，这两种调节机制紧密相连，因为迄今为止表征的大多数植物miRNA靶向TF并调节其表达和活性。菌根和非菌根M的小RNA和降解组标签的深度测序。蒺藜根中发现了数百种新的M. trunctula miRNA和miRNA切割的mRNA。在拟议的项目中，将对在菌根根中具有诱导丰度或已知参与根内共生的mRNA切割靶点的miRNA进行表征。与此同时，我们将继续分析两个降解文库，以检测在菌根根中具有特定miRNA介导的降解模式的mRNA。在该项目的第二部分，我们确定了转录因子与丛枝相关的表达，以及转录因子诱导的扩散信号来自菌根根器官培养。这些TF的特点是表达扰动分析，定位和有关的下游目标，使用诱导型表达系统。为了扩展我们对植物细胞感知AM真菌信号后的第一反应的了解，我们计划对分离的根表皮细胞的RNA进行深度测序。

The mechanisms leading to the rapid and profound reprogramming of plant cells during the arbuscular mycorrhizal (AM) symbiosis are largely unknown. The proposed projects will analyze two major levels of the regulatory network of plant cells to determine their involvement in the response to AM colonization: transcription factors (TFs) and microRNAs (miRNAs). In plants, both regulatory mechanisms are tightly linked, since the majority of plant miRNAs characterized so far target TFs and regulate their expression and activity. Deep sequencing of small RNA and degradome tags of mycorrhizal and nonmycorrhizal M. truncatula roots revealed hundreds of novel M. trunctula miRNAs and miRNA-cleaved mRNAs. MiRNAs with induced abundance in mycorrhizal roots or with mRNA-cleavage targets known to be involved in root endosymbioses will be characterized in the proposed project. In parallel, we will continue the analysis of two degradome libraries in order to detect mRNAs with specific miRNA-mediated degradation pattern in mycorrhizal roots. In the second part of the project we identified TFs with an arbuscule-related expression as well as TFs induced upon diffusible signals deriving from a mycorrhizal root organ culture. These TFs are now characterized by expression perturbation analysis, localization and concerning their downstream targets using an inducible expression system. To extend our insight in the first responses of a plant cell after perception of signals from AM fungi, we plan a deep sequencing of RNA from isolated root epidermal cells.