CAREER: Exploring the Transcriptional Regulatory Networks Controlling the Early Stages of Legume Nodulation

一群被称为根瘤菌的细菌将大气中的氮转化为一种化学形式，以支持豆科植物的生长和繁殖。这种细菌与它们的豆类宿主建立了共生关系，它们居住在根瘤中，根瘤中发育出专门的结构，以促进两个伙伴之间的营养交换。这是一个经济上重要的过程，因为它减少了种植作物所需的氮肥量，是可持续农业的关键组成部分。因此，更好地了解控制的分子机制的结晶过程中，应导致更有效的方法来捕获和固定大气中的氮的见解，并将这种能力转移到非豆科植物。在我们对豆科植物根瘤化的理解中，一个值得注意的成就是表征了控制根瘤菌感染植物根毛细胞的信号步骤，即根瘤化的初始步骤。这种共生途径由豆类根毛细胞中近2000个基因调控。研究人员将描述一个在控制早期阶段发育过程中必不可少的基因网络。除了对豆类研究的影响外，该项目更广泛的影响还包括为来自代表性不足群体的俄克拉荷马州高中和本科生制定独特的教育计划，促进研究和教育之间的强有力的整合。这个CAREER项目是建立在这样的假设之上的，即直接在共生途径的一个或几个转录因子控制下的调控网络协调了适当的生物学过程。根瘤菌对根毛细胞基因表达的激活和时机。特别关注结瘤信号通路1（NSP 1）的调控网络，该项目将解决两个关键问题：什么是大豆和苜蓿根毛基因的身份直接受NSP 1的控制？与NSP 1相关的蛋白复合物是什么？它们如何控制根毛基因在根瘤菌接种后的表达？为了回答这些问题，研究人员将1）通过高通量测序技术和应用DamID-seq或ChIP-seq方法来表征直接受转录因子GmNSP 1a和B控制的大豆根毛基因，2）鉴定接种B的根毛细胞中GmNSP 1a和B的蛋白伴侣。通过免疫共沉淀法检测根瘤菌接种后根毛细胞中蛋白质伴侣的表达，验证了大豆和模式豆科植物蒺藜苜蓿根毛基因调控网络的保守性。

A group of bacteria called rhizobia convert atmospheric nitrogen to a chemical form available to support growth and reproduction of plants in the legume family. The bacteria establish a symbiotic relationship with their legume hosts, residing in root nodules where specialized structures develop to facilitate the exchange of nutrients between the two partners. This is an economically important process as it reduces the amount of nitrogen fertilizer needed to grow crops and is a key component in sustainable agriculture. Thus, a better understanding of the molecular mechanisms controlling the nodulation process should lead to insights about more effective ways to capture and fix atmospheric nitrogen and to the transfer of this capacity to non-legume plants. One notable achievement in our understanding of legume nodulation is the characterization of the signaling steps that control the infection of the plant root hair cell by rhizobia, the initial step of nodulation. This symbiotic pathway is regulated by almost 2000 genes in legume root hair cells. The investigators will characterize a network of genes essential in controlling the early stages of nodulation. In addition to its impact on legume research, the broader impacts of this project include the development of unique educational programs dedicated to Oklahoma high-school and undergraduate students from under-represented groups, promoting strong integration between research and education.This CAREER project is built on the hypothesis that regulatory networks directly under the control of one or several transcription factors of the symbiotic pathway orchestrate the proper activation and timing of gene expression in root hair cells in response to rhizobia. Specifically focusing on the Nodulation Signaling Pathway1 (NSP1) regulatory network, this project will address two key questions: What is the identity of the soybean and medicago root hair genes directly under the control of NSP1? What are the protein complexes asscociated with NSP1 and how do they control the expression of root hair genes in response to rhizobial inoculation? To answer these questions, the investigators will 1) characterize the soybean root hair genes directly under the control of the transcription factors GmNSP1a and b in response to Bradyrhizobium japonicum through high-throughput sequencing technologies and by applying DamID-seq or ChIP-seq methods, 2) identify the protein partners of the GmNSP1a and b in root hair cells inoculated with B. japonicum by co-immunoprecipitation of the protein partners in root hair cells upon rhizobia inoculation; 3) validate the conservation of the root hair gene regulatory networks between soybean and Medicago truncatula, the model legume.