Improving symbiotic performance for enhanced plant nutrition

可持续农业实践的核心目标是提供营养食品和植物产品，同时尽量减少对环境的影响。豆科植物是可持续农业的关键组成部分，因为它们与固氮土壤细菌（根瘤菌）形成共生关系，减少了我们对施用氮肥的依赖。合成氮肥的生产消耗大量的化石燃料，并且它们的应用导致负面的环境后果（例如，温室气体排放、水资源污染）。根瘤菌属于一类称为固氮菌的细菌，其可以从惰性大气氮气中产生可用形式的氮。大气中含有78%的氮气，但植物无法直接获得必需的氮元素。根瘤菌进入豆科植物的根部，并在一个称为根瘤的特殊器官内的细胞中定居。然后根瘤菌通过将氮气转化为氨（固氮）来为植物提供氮，以换取营养。先前的工作表明，固氮速率受到细菌营养供应和结核固定氮输出速率的限制。因此，有机会探索新的策略，以提高共生固氮性能。我的项目的长期目标是了解豆类-根瘤菌共生的分子、生化和遗传机制。这将为旨在提高豆类植物在农业中的价值的战略提供知识基础。在短期内，拟议的计划旨在确定控制共生伙伴之间营养物质（代谢物和离子）交换的机制。据推测，改善营养物质的交换可以提高豆科植物的固氮率和营养价值。提高固氮速率一直是该领域研究人员的目标，并且仍然是一个有希望的机会。总的来说，多学科研究计划将解决豆类研究领域尚未解决的关键问题，并为下一代科学家提供高级培训机会。随着对植物蛋白的需求稳步增长，豆类因其对环境的影响小和富含蛋白质的种子而被定位为满足需求。这项关键的研究是及时和必要的，因为我们走向未来的更环保的农业实践在加拿大。

A central goal of sustainable agricultural practice is to provide nutritious food and plant products while minimizing the impact on the environment. Legume plants are a key component of sustainable agriculture since they form a symbiosis with nitrogen-fixing soil bacteria (rhizobia), reducing our reliance upon applied nitrogen fertilizers. The production of synthetic nitrogen fertilizers consumes vast quantities of fossil fuels and their application leads to negative environmental outcomes (e.g., greenhouse gas emissions, contamination of water resources). Rhizobia belong to a class of bacteria termed diazotrophs, organisms which can generate useable forms of nitrogen from inert atmospheric nitrogen gas. The atmosphere contains 78% nitrogen gas, yet the essential nitrogen element cannot be directly accessed by plants. Rhizobia enter into legume roots and colonize cells within a specialized organ called a root nodule. Rhizobia then provide nitrogen to the plant by converting nitrogen gas to ammonia (nitrogen fixation) in exchange for nutrients. Prior work has demonstrated that the rate of nitrogen fixation is limited by both the supply of nutrients to the bacteria as well as the rate of fixed nitrogen export out of the nodule. Therefore, there is an opportunity to explore novel strategies to increase symbiotic nitrogen fixation performance. The long-term goal of my program is to understand the molecular, biochemical, and genetic mechanisms that underlie the legume-rhizobial symbiosis. This will provide the knowledge base for strategies aimed at improving the value of legume plants in agriculture. In the short term, the proposed program aims to identify mechanisms which control the exchange of nutrients (metabolites and ions) between symbiotic partners. Improving the exchange of nutrients is hypothesized to enhance the rates of nitrogen fixation and the nutritive value of legumes. Increasing the rate of nitrogen fixation has long been a goal of researchers in the field and remains a promising opportunity. Collectively, the multi-disciplinary research program will address key unresolved questions in the field of legume research and provide advanced training opportunities for the next generation of scientists. As the demand for plant protein is steadily increasing, legumes are positioned to fulfill the need due to their low environmental impact and protein-rich seeds. This pivotal research is both timely and essential as we move towards a future of more environmentally responsible farming practices in Canada.