INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, Castanet-Tolosan, France; CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, Castanet-Tolosan, France; New Zealand Institute for Advanced Study, Massey University, Auckland, New Zealand.
Department of Microbiology, Nanjing Agricultural University, Nanjing, China; Department of Microbiology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Trends Microbiol. 2016 Jan;24(1):63-75. doi: 10.1016/j.tim.2015.10.007. Epub 2015 Nov 21.
Bacterial accessory genes are genomic symbionts with an evolutionary history and future that is different from that of their hosts. Packages of accessory genes move from strain to strain and confer important adaptations, such as interaction with eukaryotes. The ability to fix nitrogen with legumes is a remarkable example of a complex trait spread by horizontal transfer of a few key symbiotic genes, converting soil bacteria into legume symbionts. Rhizobia belong to hundreds of species restricted to a dozen genera of the Alphaproteobacteria and Betaproteobacteria, suggesting infrequent successful transfer between genera but frequent successful transfer within genera. Here we review the genetic and environmental conditions and selective forces that have shaped evolution of this complex symbiotic trait.
细菌附属基因是与宿主进化历史和未来不同的基因组共生体。附属基因包在菌株之间转移，并赋予了重要的适应能力，例如与真核生物的相互作用。通过水平转移少数关键共生基因将土壤细菌转化为豆科植物共生体从而固定氮的能力是一个复杂特征传播的显著例子。根瘤菌属于局限于α变形菌和β变形菌十几个属的数百个种，这表明属间的成功转移很少见，但属内的成功转移很频繁。在这里，我们回顾了塑造这种复杂共生特征进化的遗传和环境条件以及选择压力。
