Functional Genomics of Root Hair Infection

根毛是在根上发育的特化的单细胞器官，以增加表面积并增强养分和水分的吸收。这些细胞也是共生固氮菌感染豆科植物的场所。后一个过程涉及根毛中广泛的细胞变化，形成感染线，细菌通过感染线进入根皮层。这一过程最终形成了一种新的器官，即根瘤，细菌在其中固定大气中的氮。最终的结果是一个系统，通过该系统，细菌获得营养环境，而植物获得氮，通常是植物生长的限制性营养素。因此，根瘤菌侵染过程具有重要的农艺和生态意义。此外，感染过程，特别是在根毛内的早期阶段，提出了有趣的细胞生物学问题。这项研究将集中在根瘤菌的根毛感染上，这是共生研究中一个特征不明显和实验困难的步骤。这项研究是通过使用大豆，我们可以分离纯化的根毛克数量;数量使DNA微阵列和蛋白质组学分析的应用。在更基本的水平上，该研究允许使用现代功能基因组工具对单个植物细胞类型的细胞生物学进行详细分析。所获得的微阵列数据将提交至GEO数据库，并在接受相关稿件后公开发表。通过功能基因组分析鉴定的基因的功能将进一步通过使用RNAi技术的特异性沉默来分析。 我们还将采用比较的方法，使用大量的和不断增长的收集共生缺陷植物突变体的模式豆类，M。truncatula和L. - 是的这项工作产生的出版物将向更大的科学界详细介绍方法和结果。更广泛的影响所涉及的研究将影响各级教育：高中，本科，研究生和研究生。具体来说，为了达到更多的本科生，我们打算使用远程学习的方法，学生，在他们的家庭机构，设计DNA微阵列实验，然后在我们的实验室进行。然后，学生将通过一个专门的网站访问数据。这样，我们将把DNA微阵列资源引入到本科生物学课程的开发中。这项工作具有更广泛的生物学意义，因为它代表了少数几个可以详细研究单细胞类型（根毛）细胞生物学的系统之一。我们希望我们的研究能够解决与植物细胞生物学相关的重要基础问题;例如，极性细胞生长，细胞骨架动力学，钙信号传导等。 为了将植物基因组知识转化为作物改良，必须充分开发作物植物（如大豆）的基因组知识，以允许从模型进行信息转移。我们的研究将为大豆功能基因组学和比较豆类基因组学的发展做出贡献。大豆生物学知识的不断增长将使植物科学家能够应对未来可能影响这一重要农艺物种的新威胁和机遇。包括大豆在内的许多植物物种的基因组学的进一步发展将适应比较方法，并将为推进植物科学提供协同机会。所描述的研究提供的培训将有助于下一代植物科学家应对这些挑战。

Root hairs are specialized, single cell organs that develop on roots to increase surface area and enhance nutrient and water uptake. These cells are also the site of infection of legumes by symbiotic nitrogen fixing bacteria. This latter process involves extensive cellular changes in the root hair with the formation of an infection thread by which the bacteria gain entry into the root cortex. This process culminates in the formation of a novel organ, the nodule, in which the bacteria fix atmospheric nitrogen. The net result is a system by which the bacteria gain a nutritious environment, while the plant gains access to nitrogen, commonly a limiting nutrient for plant growth. Thus, the rhizobial infection process has great agronomic and ecological significance. Moreover, the infection process, especially during the early phases within the root hair, presents interesting cell biology questions. The research will focus on root hair infection by rhizobia, a poorly characterized and experimentally difficult step in the symbiosis to study. The research is made possible by using soybean, from which we can isolate purified root hairs in gram quantities; an amount enabling the application of both DNA microarray and proteomic analysis. At a more basic level, the research allows for the detailed analysis, using modern functional genomic tools, of the cell biology of a single, plant cell type. Microarray data obtained will be submitted to the GEO database and will be made publicly available upon acceptance of the relevant manuscript for publication. The function of genes identified by functional genomic analysis will be further analyzed by specific silencing using RNAi technology. We will also employ a comparative approach using the large and growing collection of symbiotically defective plant mutants in the model legumes, M. truncatula and L. japonicus. Publications arising from the work will detail methods and results to the larger scientific community. Broader ImpactsThe research involved will impact education at all levels: high school, undergraduate, graduate and postgraduate. Specifically, in order to reach more undergraduate students, we intend to use a distance learning method by which students, at their home institutions, design DNA microarray experiments, which then are conducted in our laboratories. The students will then have access to the data via a dedicated website. In this way, we will bring DNA microarray resources to the development of undergraduate biology curriculum. The work proposed has broader biological significance since it represents one of the few systems in which the cell biology of a single cell type, the root hair, can be studied in detail. We expect our research to address important basic questions relevant to plant cell biology; such as, polar cell growth, cytoskeleton dynamics, calcium signaling, and many others. In order to translate plant genomic knowledge into crop improvement, genomic knowledge of crop plants, such as soybean, must be developed well enough to allow information transfer from models to occur. Our research will contribute to the development of soybean functional genomics and comparative legume genomics. The increasing knowledge base of soybean biology will allow plant scientists to respond to new threats and opportunities that may impact this agronomically important species in the future. The further development of the genomics of many plant species, including soybean, will accommodate comparative approaches and will provide synergistic opportunities to advance plant science. The training provided by the research described will help prepare the next generation of plant scientists to meet these challenges.