Legacy of prior host and soil selection on rhizobial fitness in planta
Legacy of prior host and soil selection on rhizobial fitness in planta
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DOI：
10.1111/evo.13807
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发表时间：
2019-08-07
期刊：
影响因子：
3.3
通讯作者：
Tiffin, Peter
中科院分区：
文献类型：
--
作者：
Burghardt, Liana T.;Epstein, Brendan;Tiffin, Peter
测量自然环境甚至非自然环境中作用于微生物种群的选择是具有挑战性的，因为许多微生物种群经历可变选择。大多数根瘤菌存在于土壤中。然而，它们也共生地生活在豆类宿主的根瘤内，每个根瘤可以释放数千个子细胞回到土壤中。我们测试了过去的选择（即，遗传）的两种植物基因型和土壤单独影响的选择和遗传多样性的人口内的101株苜蓿Ensifermeliloti。我们还确定了与土壤和宿主依赖适应性最密切相关的等位基因变体。除了对根瘤菌种群施加直接选择外，土壤和宿主环境对宿主世代具有持久的影响。在遗产期间的主机存在和基因型解释22%和12%的变异的结核菌群的菌株组成在第二个队列，分别。虽然在遗产队列中具有高宿主适应性的菌株倾向于在第二队列中富集，但当第二队列之前是宿主而不是土壤遗产时，菌株群落的多样性更大。我们的研究结果表明，土壤选择驱动这些植物相关微生物的进化的潜在重要性。
Measuring selection acting on microbial populations in natural or even seminatural environments is challenging because many microbial populations experience variable selection. The majority of rhizobial bacteria are found in the soil. However, they also live symbiotically inside nodules of legume hosts and each nodule can release thousands of daughter cells back into the soil. We tested how past selection (i.e., legacies) by two plant genotypes and by the soil alone affected selection and genetic diversity within a population of 101 strains of Ensifer meliloti. We also identified allelic variants most strongly associated with soil- and host-dependent fitness. In addition to imposing direct selection on rhizobia populations, soil and host environments had lasting effects across host generations. Host presence and genotype during the legacy period explained 22% and 12% of the variance in the strain composition of nodule communities in the second cohort, respectively. Although strains with high host fitness in the legacy cohort tended to be enriched in the second cohort, the diversity of the strain community was greater when the second cohort was preceded by host rather than soil legacies. Our results indicate the potential importance of soil selection driving the evolution of these plant-associated microbes.