Plasmid biology of Rhizobium leguminosarum

根瘤菌是以其在豆科植物如豌豆、菜豆、扁豆和苜蓿的根部形成固氮根瘤的能力而闻名的细菌。它们允许这些植物在不添加合成含氮肥料的情况下生长的能力，其生产和应用在化石燃料消耗中具有高成本，使得它们在可持续农业中极其重要。生产更有效和更有竞争力的根瘤菌菌株用作豆类接种剂是生物技术的主要目标。然而，引入的根瘤菌菌株的相互作用，并在环境中的菌株之间的遗传转移的潜力，没有得到很好的理解。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，其中一些质粒的性质介于质粒和染色体之间。该提案将重点关注以下质粒：

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