Improving symbiotic performance for enhanced plant nutrition

可持续农业做法的一个中心目标是提供营养食品和植物产品，同时将对环境的影响降至最低。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，减少了我们对所施氮肥的依赖。合成氮肥的生产消耗大量的化石燃料，其使用会导致负面的环境后果(例如温室气体排放、水资源污染)。根瘤菌属于一类被称为重氮菌的细菌，这种微生物可以从惰性大气氮气中产生可利用的氮气。大气中含有78%的氮气，但植物无法直接获取必需的氮素。根瘤菌进入豆科植物的根部，并在称为根瘤的特殊器官内定植细胞。然后，根瘤菌通过将氮气转化为氨(固氮)来向植物提供氮素，以换取养分。先前的工作已经证明，固氮速度既受到向细菌提供的营养物质的限制，也受到根瘤输出固定氮的速度的限制。因此，有机会探索新的策略来提高共生固氮性能。我这个项目的长期目标是了解豆科植物-根瘤菌共生的分子、生化和遗传机制。这将为旨在提高豆科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。改善营养物质的交换被认为是为了提高豆类的固氮率和营养价值。提高固氮率一直是该领域研究人员的目标，仍然是一个有希望的机会。总体而言，多学科研究计划将解决豆科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。随着对植物蛋白需求的稳步增长，豆类因其对环境的低影响和富含蛋白质的种子而处于满足需求的地位。在我们迈向加拿大更具环境责任感的农业实践的未来之际，这项关键的研究既及时又至关重要。

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.