Cooperation and Conflict in the Legume-Rhizobium Symbiosis

豆科植物-根瘤菌共生中的合作与冲突

• 批准号: 0077903
• 负责人: Robert Ford Denison
• 金额: $ 12.26万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-15 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0077903&HistoricalAwards=false
• 关键词: Cooperation; Conflict; Legume; Rhizobium; Symbiosis

Legumes, such as clover, alfalfa, and soybean, are important in agricultureand in nature. Soil bacteria known as rhizobia can benefit legumes whenthey infect their roots, because they can take up atmospheric nitrogen andsupply it to the plant. This extra nitrogen increases plantphotosynthesis, thereby indirectly increasing the energy supply to therhizobia. Thus, symbiosis between legume and rhizobium seems beneficial toboth. But what if, as often happens, two or more different strains ofrhizobia infect the same plant? An initially rare strain that uses plantresources for its own reproduction, rather than for nitrogen fixation,could increase in numbers at the expense of both the plant and the morecooperative rhizobial strain. Although most rhizobia seem to bepredominantly beneficial, such "parasitic" strains do exist.This research will determine whether plant responses to rhizobia that failto fix nitrogen can select for more beneficial rhizobia. Previous researchshows that legumes can control the oxygen supply to rhizobia inside theirroot nodules. The PIs will determine how this oxygen supply changes withchanges in nitrogen fixation by rhizobia, and how this legume responseaffects the survival and reproduction of the rhizobia. Most of theresearch will be conducted under controlled laboratory conditions, but afield test will determine whether legumes alter the frequency ofcooperative vs. parasitic rhizobia in soil. In addition to possiblepractical applications in agriculture, the research will contribute tooverall understanding of the general problem of cooperation betweenspecies. Such cooperation is critical to the pollination of flowers, thesurvival and growth of coral reefs, plant growth in phosphorus-poor soils,and many other natural systems.

豆类，例如三叶草，苜蓿和大豆，在自然界中很重要。 被称为根瘤菌的土壤细菌可以使豆类感染其根部，因为它们可以吸收大气氮并将其供应到植物上。 这种额外的氮可以增加植物学合成，从而间接增加了对毒液的能源供应。 因此，豆科植物和根茎之间的共生似乎是有益的。 但是，如果经常发生的两种或更多不同的rhizobia菌株感染了同一植物怎么办？ 最初使用Plantresources进行自身繁殖而不是固定氮的菌株，可能会以植物和不可恢复的根瘤菌菌株为代价增加数量。 尽管大多数根瘤菌似乎似乎是有益的，但确实存在这种“寄生”菌株。这项研究将确定植物对无法修复氮的根瘤菌的反应是否可以选择更有益的根瘤菌。 先前的研究表明，豆类可以控制其根部结节内根瘤菌的氧气供应。 PI将确定这种氧供应如何随根茎固定氮固定的变化以及该豆类反应反应的变化而变化。 大部分搜索将在受控的实验室条件下进行，但是露天测试将决定豆类是否会改变土壤中合作术与寄生性根瘤菌的频率。 除了可能在农业中的实践应用外，这项研究还将有助于对合作的一般问题的理解。 这种合作对于花朵的授粉，珊瑚礁的繁殖和生长至关重要，磷土壤中的植物生长以及许多其他天然系统至关重要。