• Legumes establish nitrogen-fixing symbioses with rhizobia. On the contrary, they can be attacked concomitantly by pathogens, raising the question of potential trade-offs between mutualism and immunity.
• In order to study such trade-offs, we used a tripartite system involving the model legume Lotus japonicus, its rhizobial symbiont Mesorhizobium loti and the soilborne pathogen Ralstonia solanacearum. We investigated the impact of mutualism on plant defense and the reciprocal influence of plant defense on mutualism.
• We found that Lotus age-related resistance against Ralstonia was improved by the interaction with rhizobia especially when nodulation is triggered. Conversely, age-related resistance did not compromise nodule organogenesis or functioning under pathogen attack. Proteomic characterization indicates that this resistance is associated with distinct proteome modifications in roots and nodules.
• This resistance questions the concept of interference between efficient defense reactions and mutualistic interactions and is of great interest for agricultural purposes as it not only restricts pathogen colonization, but would also preserve nitrogen fixation and yield.

中文翻译：

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Mesorhizobium 增强了莲花对 Ralstonia 的抵抗力，并且不会损害共生关系

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  豆科植物与根瘤菌建立固氮共生关系。相反，它们可能同时受到病原体的攻击，这引发了共生和免疫之间潜在权衡的问题。
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  为了研究这种权衡，我们使用了一个三方系统，涉及模型豆科植物 Lotus japonicus、其根瘤共生体 Mesorhizobium loti 和土壤传播病原体 Ralstonia solanacearum。我们研究了共生主义对植物防御的影响以及植物防御对共生主义的互惠影响。
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  我们发现，与根瘤菌的相互作用改善了莲花对 Ralstonia 的年龄相关抵抗力，尤其是在触发结瘤时。相反，与年龄相关的抵抗不会损害结节器官发生或在病原体攻击下的功能。蛋白质组学特征表明，这种抗性与根和根瘤中不同的蛋白质组修饰有关。
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  这种抗性对有效防御反应和互惠相互作用之间干扰的概念提出了质疑，并且对农业目的具有极大的兴趣，因为它不仅限制了病原体的定植，而且还会保持固氮和产量。