Don't go out there! How do bacteria-phages interactions in the soil impact the rhizobia-legume symbiosis

根瘤菌（固氮菌）是典型的互惠互动模式-它们与豆类形成亲密的细胞内共生，在那里它们交换氮以获得营养和庇护。根瘤菌与豆科植物的共生关系一直被认为是一种成对的相互作用，但实际上它是一个复杂的物种群落，在植物与宿主之间，根瘤菌作为自由生活的细菌生活在不同的土壤微生物群落中，包括细菌的主要捕食者--细菌病毒。噬菌体捕食可以通过多种方式塑造根瘤菌-豆科植物的共生关系;噬菌体捕食驱动对噬菌体抗性的持续选择（拮抗协同进化），这可能导致共生关系中的多效性权衡。相反，外部较高的死亡率可能会通过增加植物内部的保护价值来推动更大的共生投资，即改变相互作用的“经济学”。在这个项目中，我们将结合联合收割机实验进化、下一代测序和植物模型来提出一个被忽视的关键问题--宿主外的相互作用如何塑造根瘤菌-豆类共生关系

Rhizobia (nitrogen-fixing bacteria) are a classic model formutualistic interactions - they form intimate intracellularsymbioses with legumes where they exchange nitrogen fornutrients and shelter. The rhizobia-legume symbiosis has beenstudied near-exclusively as a pairwise interaction, but in realityis embedded within a complex species community withconsequences for each partner and thus the symbiosis.Between plant-hosts rhizobia live as free-living bacteria within adiverse soil microbial community including phages (bacterialviruses) - the primary predators of bacteria. Phage predationcould shape the rhizobia-legume symbiosis in numerous ways;phages drive continuous selection for phage resistance(antagonistic coevolution) which may result in pleiotropic trade-offs in the symbiosis. Conversely, higher mortality outside maydrive greater symbiotic investment by increasing the value ofprotection within the plant, i.e. altering the 'economics' of theinteraction. In this project we will combine experimentalevolution, next-generation sequencing and mathematicalmodelling to ask a critical overlooked question - how dointeractions outside the host shape the rhizobia-legumesymbiosis