Discordant population structure among rhizobium divided genomes and their legume hosts
Discordant population structure among rhizobium divided genomes and their legume hosts
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DOI：
10.1111/mec.16704
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发表时间：
2022-10-05
影响因子：
4.9
通讯作者：
Heath，Katy D.
中科院分区：
文献类型：
--
作者：
Riley，Alex B.;Grillo，Michael A.;Heath，Katy D.
共生现象往往发生在具有不同生活史特征和扩散机制的伙伴之间。许多细菌共生体的基因组包含具有不同进化速率和水平传播的多个复制子。这种差异可能会导致宿主和共生体之间以及细菌共生体分裂基因组元件之间的种群结构差异。这些差异可能反过来塑造共生相互作用和细菌进化的演变。在这里，我们使用全基因组重测序的分层结构的样品的191菌株的Sinorhizobium meliloticcollected从21个地点在欧洲南部，以表征人口结构的细菌共生体，形成了根瘤共生与宿主植物苜蓿。苜蓿基因组显示出高的本地（网站内）的变化和距离隔离很小。这对于两个共生元件pSymA和pSymB尤其如此，它们具有彼此相似的群体结构，但与细菌染色体和宿主植物不同。由于染色体上有限的重组，与共生元素相比，不同的种群结构可能会导致有效基因流的差异。或者，阳性或纯化选择，很少重组，可以解释染色体上不同的地理模式。宿主和共生体之间不一致的种群结构表明，在该范围的不同部分，地理和遗传上不同的宿主种群可能与遗传上相似的共生体相互作用，可能会最大限度地减少当地的专业化。
Symbiosis often occurs between partners with distinct life history characteristics and dispersal mechanisms. Many bacterial symbionts have genomes comprising multiple replicons with distinct rates of evolution and horizontal transmission. Such differences might drive differences in population structure between hosts and symbionts and among the elements of the divided genomes of bacterial symbionts. These differences might, in turn, shape the evolution of symbiotic interactions and bacterial evolution. Here we use whole genome resequencing of a hierarchically structured sample of 191 strains ofSinorhizobium meliloticollected from 21 locations in southern Europe to characterize population structures of this bacterial symbiont, which forms a root nodule symbiosis with the host plantMedicago truncatula.S. melilotigenomes showed high local (within‐site) variation and little isolation by distance. This was particularly true for the two symbiosis elements, pSymA and pSymB, which have population structures that are similar to each other, but distinct from both the bacterial chromosome and the host plant. Given limited recombination on the chromosome, compared to the symbiosis elements, distinct population structures may result from differences in effective gene flow. Alternatively, positive or purifying selection, with little recombination, may explain distinct geographical patterns at the chromosome. Discordant population structure between hosts and symbionts indicates that geographically and genetically distinct host populations in different parts of the range might interact with genetically similar symbionts, potentially minimizing local specialization.