Table_2_Modulation of the Wheat Seed-Borne Bacterial Community by Herbaspirillum seropedicae RAM10 and Its Potential Effects for Tryptophan Metabolism in the Root Endosphere.DOCX

Plants and their associated microbiota share ecological and evolutionary traits that are considered to be inseparably woven. Their coexistence foresees the use of similar metabolic pathways, leading to the generation of molecules that can cross-regulate each other’s metabolism and ultimately influence plant phenotype. However, the extent to which the microbiota contributes to the overall plant metabolic landscape remains largely unexplored. Due to their early presence in the seed, seed-borne endophytic bacteria can intimately colonize the plant’s endosphere while conferring a series of phytobeneficial services to their host. Understanding the dynamics of these endophytic communities is a crucial step toward the formulation of microbial inoculants that can modulate the functionality of the plant-associated microbiota for improved plant fitness. In this work, wheat (Triticum aestivum) roots non-inoculated and inoculated with the bacterium Herbaspirillum seropedicae strain RAM10 were analyzed to explore the impact of inoculant–endophyte–wheat interrelationships on the regulation of tryptophan (Trp) metabolism in the endosphere environment. Root inoculation with H. seropedicae led to phylum-specific changes in the cultivable seed-borne endophytic community. This modulation shifted the metabolic potential of the community in light of its capacity to modulate the levels of key Trp-related metabolites involved in both indole-3-acetic acid (IAA) biosynthesis and in the kynurenine pathway. Our results support a mode of action of H. seropedicae relying on a shift in both the composition and functionality of the seed-borne endophytic community, which may govern important processes such as root growth. We finally provide a conceptual framework illustrating that interactions among roots, inoculants, and seed-borne endophytes are critical to fine-tuning the levels of IAA in the endosphere. Understanding the outcomes of these interactions is a crucial step toward the formulation of microbial inoculants based on their joint action with seed-borne endophytic communities to promote crop growth and health in a sustainable manner.

植物及其相关的微生物群落共享着被视为不可分割的生态和进化特性。它们的共存预示着利用相似的代谢途径，进而产生能够相互调节对方代谢并最终影响植物表型的分子。然而，微生物群落对植物整体代谢景观的贡献程度仍 largely 尚未充分探索。由于它们在种子中的早期存在，种子携带的内生细菌可以亲密地定殖于植物的内在空间，同时向其宿主提供一系列的植物益处服务。理解这些内生微生物群落的动态变化是制定能够调节与植物相关微生物群落功能以改善植物适应性的微生物接种剂的至关重要的步骤。在本研究中，分析了未接种和接种有 Herbaspirillum seropedicae 稀释菌株 RAM10 的小麦（Triticum aestivum）根系，以探讨接种剂-内生菌-小麦之间相互关系对内在环境中色氨酸（Trp）代谢调控的影响。Herbaspirillum seropedicae 的根系接种导致了可培养的种子携带内生菌群落门水平的特异性变化。这种调节根据其调节关键 Trp 相关代谢物水平的能力，改变了群落的代谢潜力，这些代谢物既参与吲哚-3-乙酸（IAA）的生物合成，也参与犬尿氨酸途径。我们的结果支持了一种作用模式，即 Herbaspirillum seropedicae 通过改变种子携带内生菌群落的组成和功能来实现，这可能控制如根系生长等重要过程。我们最终提供了一个概念框架，说明了根系、接种剂和种子携带内生菌之间的相互作用对于精确调节内在空间中 IAA 水平至关重要。理解这些相互作用的后果是制定基于与种子携带内生菌群落联合作用的微生物接种剂以可持续促进作物生长和健康的关键步骤。