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新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AM侵染的反应：转录因子(TF)和microRNAs(MiRNAs)。在植物中，这两种调控机制是紧密相连的，因为到目前为止，大多数植物miRNAs都以转录因子为靶标，并调节它们的表达和活性。对菌根和非菌根根部的小RNA和降解组标记进行了深度测序，发现了数百个新的干枝杆菌miRNAs和miRNA裂解的mRNAs。在拟议的项目中，将描述在菌根中诱导丰度或具有已知的参与根内共生的mRNA切割靶标的miRNAs。同时，我们将继续分析两个降解组文库，以检测菌根中具有特定miRNA介导的降解模式的mRNAs。在项目的第二部分，我们确定了与丛枝相关的表达的转录因子，以及来自菌根器官培养的可扩散信号诱导的转录因子。这些转录因子现在通过表达扰动分析、定位和使用可诱导表达系统涉及其下游靶标来表征。为了扩展我们对植物细胞在感知AM真菌信号后的第一反应的洞察力，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.