Introducing Biological Nitrogen Fixation to Plants

将生物固氮引入植物

• 批准号: RGPIN-2015-04886
• 负责人: Good, Allen
• 金额: $ 2.48万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614477
• 关键词: Introducing; Biological; Nitrogen; Fixation; Plants

Nitrogen is the main limiting nutrient for crops, and we currently synthesize over 100MMt of fertilizer annually. This revolutionized crop yield but at substantial economic and environmental costs (Good and Beatty, 2011). However, if we are to feed the future 9B people on the planet in 2050, we would need to increase the amount of fixed N by an additional 51MMt. Even if this was possible, the environmental consequences would be so significantly deleterious as to bring new meaning to the statement, “To foul your own nest”. Therefore there is no question that we need to address the ways in which we fix N, either through the production of N based fertilizers or by biological nitrogen fixation (BNF). This level of fixed N for agriculture is unsustainable, Industrially fixed N (IFN) is produced using the Haber-Bosch process. However, certain microorganisms have the ability to fix atmospheric nitrogen under ambient temperature and pressure conditions. In principle, the ability to biologically-fixed nitrogen could be introduced into plants, allowing them to fix atmospheric nitrogen directly and when needed. This would keep the environment almost “untouched”, by eliminating excess N loss into the environment. This proposal focuses on implementing a series of experiments that will allow us to determine whether it is possible to introduce biological N fixation into crop plants. IFN requires significant amounts of energy both to produce and ship, while biologically-fixed nitrogen influences the global nitrogen cycle substantially less than IFN. Recently there has been renewed interest in bioengineering N2 fixing cereals and significant advances in our understanding of the biology of N2 fixation have been made in the last two decades. We now understand the complete biosynthesis pathway for nitrogenase, the enzyme that performs the BNF reaction, and we are in a position to assay each step in the assembly pathway in vitro. Finally, with the rapid advances in synthetic biology, we can now synthesize novel genes, regulatory components and pathways and introduce them into organisms of our choice. N2-fixing cereal crops would benefit developed area farmers (ie Alberta) by lowering N fertilizer expenses while developing area farmers would have access to N2 fixing cereal plants. We want to reduce the cereal crop dependence on applied fertilizers by engineering crop plants that fix their own nitrogen to sustain growth and yield. This is a timely project that will build on decades of research on the N2 fixing bacteria/plant symbioses, the genetic and protein components of the bacterial N2 fixing nitrogenase complex, the full genomic sequences of cereal organelle genomes, and the recent development of techniques for the transient expression of multiple genes.

氮是作物的主要限制性营养素，目前我们每年合成超过1亿吨肥料。这彻底改变了作物产量，但付出了巨大的经济和环境代价（Good和Beatty，2011）。然而，如果我们要在2050年养活地球上未来的90亿人，我们需要将固定氮的数量增加5100万吨。即使这是可能的，环境后果将是如此严重的有害，使新的含义的声明，“弄脏自己的窝”。因此，毫无疑问，我们需要解决我们固定氮的方式，无论是通过生产氮基肥料还是通过生物固氮（BNF）。这种农业固定氮的水平是不可持续的，工业固定氮（IFN）是使用哈伯-博施工艺生产的。然而，某些微生物具有在环境温度和压力条件下固定大气氮的能力。原则上，可以将生物固定氮的能力引入植物，使它们能够在需要时直接固定大气氮。这将通过消除过量的N损失到环境中来保持环境几乎“不受影响”。这项建议的重点是实施一系列的实验，这将使我们能够确定是否有可能将生物固氮引入作物。IFN需要大量的能量来生产和运输，而生物固定氮对全球氮循环的影响远小于IFN。最近，人们对生物工程固氮谷物重新产生了兴趣，在过去的二十年里，我们对固氮生物学的理解取得了重大进展。我们现在了解了固氮酶的完整生物合成途径，这种酶进行BNF反应，我们能够在体外分析组装途径中的每一步。最后，随着合成生物学的快速发展，我们现在可以合成新的基因、调控成分和途径，并将它们引入我们选择的生物体中。 固氮谷类作物将有利于发达地区的农民（即阿尔伯塔），降低氮肥费用，而发展中地区的农民将有机会获得固氮谷类植物。我们希望通过改造作物植物来减少谷类作物对施用肥料的依赖，这些作物植物可以固定自己的氮以维持生长和产量。这是一个及时的项目，将建立在几十年的研究固氮细菌/植物共生，细菌固氮酶复合物的遗传和蛋白质组分，谷物细胞器基因组的全基因组序列，以及最近开发的多个基因的瞬时表达技术。