RESEARCH-PGR: System approaches to study soybean root biology at high resolution

大豆是一种主要作物，具有与土壤细菌共生固定大气氮的能力。像大豆这样的豆类每年固定6000万吨氮，这些氮的肥料替代价值为70-100亿美元。氮气固定研究的长期目标是将豆类的共生能力转移到玉米或番茄等非豆类作物上。然而，我们对细菌穿透根部后发生的复杂事件的理解存在差距。这些差距阻碍了在非豆科植物中设计固氮技术的努力。因此，这个项目的主要目标是阐明在调节细菌通过根部移动的结构形成过程中发生的初始事件。该项目将使用高分辨率方法在单细胞水平上表征大分子事件。实验数据将用复杂的建模工具进行分析，以提高我们对导致共生的豆类-细菌相互作用的第一个事件的理解。所获得的知识将支持将根瘤菌共生转移到非豆科植物的努力。除了研究任务，该项目还将创建新的项目，以提供变革性的基础教育，以及为初中和高中教师的专业发展提供培训项目。最后，这个项目将开发一个创新的二年级生物信息学/植物科学计划，以提供植物研究和生物信息学的综合培训。复杂生物过程的数据集成和系统建模需要详细的、功能强大的基因组数据，最好以特定细胞的方式获得，以避免由于无反应细胞的存在而导致的信号稀释的影响。该项目的长期目标是加深对大豆氮素固定共生的基本认识。该项目的一个独特的重点是能够在单细胞分辨率下采样和分析转录组、蛋白质组和代谢组。这些方法以及复杂的数据分析和建模工具将应用于大豆结瘤的中间阶段；具体地说，将应用于侵染丝线进展和细菌进入根瘤细胞的过程。这些是结核形成/功能中的关键事件，在很大程度上仍未确定。生成的数据将用于构建植物对根瘤菌感染丝线启动和生长的预测计算模型。从这项研究中获得的知识，加上精确育种技术，将有助于提高大豆质量，满足预计在未来几年对食品和燃料日益增长的需求。此外，填补我们对根瘤菌-豆科植物感染过程的理解空白，对于将这种共生转移到非豆科植物(如玉米)的持续努力将是至关重要的。该项目还包括强大的推广计划，重点是向小学生、高中生和本科生介绍植物科学。

Soybean is a major crop with the ability to fix atmospheric nitrogen through symbiosis with soil bacteria. Legumes like soybean annually fix 60 million metric tons of nitrogen, which have a fertilizer replacement value of $7- 10 billion. A long-term goal of N2 fixation research is to transfer the symbiotic ability of legumes to non-legume crops like corn or tomato. However, there are gaps in our understanding of the complex events that occur after the bacteria penetrate the root. These gaps are hindering efforts to engineer nitrogen fixation into non-legumes. Hence, the main objective of this project is to elucidate the initial events that take place during the formation of structures that mediate the movement of bacteria through the root. This project will use high-resolution methods to characterize macromolecular events at a single-cell level. The experimental data will be analyzed with sophisticated modeling tools to improve our understanding of the first events of the legume-bacterial interactions that lead to symbiosis. The knowledge gained will support efforts to transfer the rhizobial symbiosis to non-leguminous plants. In addition to the research mission, the project will create new programs to provide transformative elementary education, as well as training programs for the professional development of middle school and high school teachers. Finally, this project will develop an innovative Sophomore Bioinformatics/Plant Science program to provide integrated training in plant research and bioinformatics.Data integration and system modeling of complex biological processes require detailed, functional genomic data, preferably obtained in a cell-specific way in order to avoid the effects of signal dilution due to the presence of non-responding cells. The long-term goal of this project is to further basic understanding of the agronomically important soybean N2 fixing symbiosis. A unique focus of this project is the ability to sample and analyze the transcriptome, proteome and metabolome at a single-cell resolution. These methods, as well as sophisticated data analysis and modeling tools, will be applied to the intermediate stages of soybean nodulation; specifically, the infection thread progression and bacterial release into nodule cells. These are key events in nodule formation/function that remain largely undefined. The data generated will be used to construct predictive, computational models of the plant response to rhizobial infection thread initiation and growth. The knowledge gained from this research, together with precision breeding techniques, will be instrumental to improving soybean quality and meeting the growing demand for food and fuel expected in the forthcoming years. Moreover, filling in the gaps in our understanding of the rhizobial-legume infection process will be critical to ongoing efforts to transfer this symbiosis to non-leguminous plants (e.g., maize). The project also includes strong outreach programs focusing on the introduction of plant science to elementary, high school and undergraduate students.