Perception of long-chain N-acyl homoserine lactones in plants

监测周围环境的能力对植物来说是至关重要的。微生物衍生分子、效应蛋白和细菌群体感应分子（QSM）在植物体内引发特异性反应。QS分子通常用于细菌群体内的细胞间通信。在植物中，QSMs诱导多种反应，例如由Sinorhizobium meliloti合成的n -3-氧-十四烷醇- l-高丝氨酸内酯（oxo-C14-HSL），以增强拟南芥和大麦的防御能力：增加胼胶沉积、酚类化合物的积累和细胞壁的木质化。此外，氧化脂素和水杨酸水平的增加有利于气孔关闭，以应对病原体。虽然对细菌（LuxR家族）和动物（PPAR受体和IQGAP1 g蛋白）的AHL感知了解很多，但对植物AHL识别的了解仍然很少。我们在这个项目中的目标是表征植物AHL感知机制。我们将使用三种独立的策略：i)由于已知细菌和动物的受体，与植物蛋白的序列相似性表明许多候选蛋白具有部分同源性。这些蛋白质将成为我们基于候选方法的重点，其中将筛选各自的突变体以进行AHL效应；ii)在下拉/MS-MS和蛋白质微阵列方法中，我们将靶向与修饰ahl结合的蛋白质。ahl结合复合物的这种表征将允许鉴定与QS分子直接相互作用的蛋白质。在这里，我们将使用新合成的带有生物素标签或光活化叠氮基团的分子；iii)拟南芥种内遗传变异潜力巨大。对不同拟南芥生态型的分析表明，它们对oxo-C14-HSL的反应存在显著差异，表明一些生态型对ahl不敏感，而另一些生态型对该分子有反应。我们的第三个策略将使用选择的重组自交系（RILs），并允许在拟南芥基因组上绘制ahl响应位点（或位点）。所有的策略都将以一个验证步骤来结束，在这个验证步骤中，确定的候选分子将在独立的技术中进行测试，包括表面等离子体共振波谱仪和RNAi。我们期望发现一系列ahl相互作用的伙伴，这将作为理解植物ahl感知的范例。除了AHL感知能力外，植物还能够影响培养基中AHL的积累。与Klug和Hackenberg小组合作，我们将研究植物信号对s . meliloti生产oxo-C14-HSL的影响。AHL对植物和植物对AHL生产的相互影响的表征将为王国间的交流提供新的见解，并为未来在新农业战略中实施所获得的知识提供微调。

The ability to monitor the surroundings is for plant of crucial importance. Microorganism-derived molecules, effector proteins and bacterial quorum sensing molecules (QSM) trigger specific reactions in plant organism. QS molecules are usually used for cell-to-cell communication within bacterial populations. In plants, QSMs induce multiple reactions, for example N-3-oxo-tetradecanoyl-L-homoserine lactone (oxo-C14-HSL) synthesized by Sinorhizobium meliloti primes Arabidopsis and barley for enhanced defense: augmented callose deposition, accumulation of phenolic compounds, and lignification of cell walls. Furthermore, increased levels of oxylipins and salicylic acid favor stomatal closure in response to pathogen. Although much is know on AHL perception in bacteria (LuxR family) and animals (PPAR receptors and the IQGAP1 G-protein), the knowledge on AHL recognition in plants is still very poor. Our goal in this project is to characterize AHL perception mechanism(s) in plants. We will use three independent strategies: i) Since the receptors of bacteria and animals are known, sequence similarities to plant proteins indicated a number of candidates with partial homologies. These proteins will be in focus of our candidate-based approach in which the respective mutants will be screened for the AHL effect; ii) In the pull-down/MS-MS and protein microarray approaches we will target proteins binding to modified AHLs. This characterization of AHL-binding complexes will allow an identification of proteins directly interacting with QS molecules. Here we will use newly synthesized molecules with a biotin tag or a photo-activated azide group; iii) The genetic variability within the Arabidopsis thaliana species bears a great potential. Analysis of different A. thaliana ecotypes revealed already a significant difference in the response to oxo-C14-HSL, indicating that some ecotypes are AHL-insensitive, whereas others respond to this molecule. Our third strategy will use chosen recombinant inbred lines (RILs) and allows the mapping of AHL-responsive locus (or loci) on the Arabidopsis genome. All strategies will be concluded with a verification step in which the identified candidates will be tested in independent techniques, including a surface plasmon resonance spectroscope and RNAi. We expect to uncover an array of AHL-interacting partners, which will serve as paradigm for the understanding of AHLs perception in plants. In addition to the ability of AHL perception, plants are able to influence the accumulation of AHLs in the medium. In collaboration with the group Klug and Hackenberg we will study the impact of plant signal(s) at the production of oxo-C14-HSL in S. meliloti. The characterization of the reciprocal impact of AHLs on plants and plants on AHL production will provide new insights into inter-kingdom communication and allow a fine-tuning for the future implementation of the gained knowledge in novel agricultural strategies.