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

监测周围环境的能力对工厂至关重要。微生物衍生的分子、效应蛋白和细菌群体感应分子（QSM）在植物体内触发特异性反应。QS分子通常用于细菌群体内的细胞间通讯。在植物中，QSM诱导多种反应，例如由苜蓿中华根瘤菌引发拟南芥和大麦合成的N-3-氧代-十四酰基-L-高丝氨酸内酯（氧代-C14-HSL），用于增强防御：增加胼胝质沉积、酚类化合物积累和细胞壁木质化。此外，增加水平的氧脂素和水杨酸有利于气孔关闭响应病原菌。虽然对细菌（LuxR家族）和动物（PPAR受体和IQGAP 1 G蛋白）中的阿勒感知了解很多，但对植物中的阿勒识别的了解仍然非常少。我们在这个项目中的目标是表征植物中的阿勒感知机制。我们将使用三个独立的策略：i）由于细菌和动物的受体是已知的，与植物蛋白的序列相似性表明了许多具有部分同源性的候选者。这些蛋白质将是我们基于候选人的方法的焦点，其中将针对阿勒效应筛选相应的突变体; ii）在下拉/MS-MS和蛋白质微阵列方法中，我们将靶向与修饰的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分子与生物素标签或光活化叠氮基; iii）拟南芥物种内的遗传变异性具有很大的潜力。分析了不同的A.拟南芥生态型已经揭示了对oxo-C14-HSL的反应的显著差异，表明一些生态型是AHL不敏感的，而其他生态型对该分子有反应。我们的第三个策略将使用选定的重组自交系（RILs），并允许定位拟南芥基因组上的AHL反应基因座（或基因座）。所有策略都将通过验证步骤得出结论，在该步骤中，将在独立的技术中对所确定的候选物进行测试，包括表面等离子体共振光谱仪和RNAi。我们希望发现一系列的AHL相互作用的合作伙伴，这将作为范式的理解AHL感知植物。除了阿勒感知能力之外，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中oxo-C14-HSL生产的影响。苜蓿草。AHL对植物和植物对阿勒生产的相互影响的表征将为王国间的交流提供新的见解，并为未来在新的农业战略中实施所获得的知识进行微调。

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.