Plasmid biology of Rhizobium leguminosarum

根瘤菌是一种在豆科植物（如豌豆、黄豆、扁豆和苜蓿）根部形成固氮根瘤的能力显著的细菌。它们能够使这些植物在不添加含氮合成肥料的情况下生长，而含氮合成肥料的生产和施用在化石燃料消耗方面成本很高，这使得它们在可持续农业中极其重要。生产更有效和更具竞争力的根瘤菌菌株作为豆科植物的接种剂是生物技术的主要目标。然而，引入的根瘤菌菌株之间的相互作用，以及菌株之间在环境中遗传转移的可能性，还没有得到很好的了解。根瘤菌在细菌中是不寻常的，因为它们具有大而复杂的基因组，通常由一条染色体和几个非常大的染色体外遗传元件（称为质粒）组成。质粒往往非常稳定，其中一些表现出介于质粒和染色体之间的特性。本提案将集中于的质粒

Rhizobia are bacteria that are notable for their ability to form nitrogen-fixing nodules on the roots of legume plants, such as peas, beans, lentils and alfalfa. Their ability to allow these plants to grow without addition of synthetic nitrogen-containing fertilizers, whose production and application has a high cost in fossil fuel consumption, makes them extremely important in sustainable agriculture. Production of more efficient and more competitive rhizobial strains for use as legume inoculants is a major goal in biotechnology. However, the interactions of introduced rhizobial strains, and the potential for genetic transfer between strains in the environment, are not well understood. Rhizobia are unusual among bacteria in that they have large and complex genomes that usually consist of one chromosome and several very large extrachromosomal genetic elements known as plasmids. The plasmids tend to be very stable, and some of them exhibit properties intermediate between those expected of a plasmid and those of a chromosome. This proposal will focus on the plasmids of