Plants grow within a complex web of species that interact with each other and with the plant 1 – 10 . These interactions are governed by a wide repertoire of chemical signals, and the resulting chemical landscape of the rhizosphere can strongly affect root health and development 7 – 9 , 11 – 18 . Here, to understand how interactions between microorganisms influence root growth in Arabidopsis , we established a model system for interactions between plants, microorganisms and the environment. We inoculated seedlings with a 185-member bacterial synthetic community, manipulated the abiotic environment and measured bacterial colonization of the plant. This enabled us to classify the synthetic community into four modules of co-occurring strains. We deconstructed the synthetic community on the basis of these modules, and identified interactions between microorganisms that determine root phenotype. These interactions primarily involve a single bacterial genus ( Variovorax ), which completely reverses the severe inhibition of root growth that is induced by a wide diversity of bacterial strains as well as by the entire 185-member community. We demonstrate that Variovorax manipulates plant hormone levels to balance the effects of our ecologically realistic synthetic root community on root growth. We identify an auxin-degradation operon that is conserved in all available genomes of Variovorax and is necessary and sufficient for the reversion of root growth inhibition. Therefore, metabolic signal interference shapes bacteria–plant communication networks and is essential for maintaining the stereotypic developmental programme of the root. Optimizing the feedbacks that shape chemical interaction networks in the rhizosphere provides a promising ecological strategy for developing more resilient and productive crops. Experiments using an ecologically realistic 185-member bacterial synthetic community in the root system of Arabidopsis reveal that Variovorax bacteria can influence plant hormone levels to reverse the inhibitory effect of the community on root growth.

中文翻译：

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单一细菌属在复杂的微生物组中维持根部生长

植物生长在复杂的物种网络中，物种之间以及与植物之间相互作用 1 – 10 。这些相互作用受到广泛的化学信号的控制，由此产生的根际化学景观可以强烈影响根系的健康和发育 7 – 9 , 11 – 18 。在这里，为了了解微生物之间的相互作用如何影响拟南芥根部生长，我们建立了植物、微生物和环境之间相互作用的模型系统。我们给幼苗接种了由 185 个成员组成的细菌合成群落，操纵非生物环境并测量了植物的细菌定植。这使我们能够将合成群落分为四个共存菌株模块。我们在这些模块的基础上解构了合成社区，并确定了决定根表型的微生物之间的相互作用。这些相互作用主要涉及单一细菌属（Variovorax），它完全逆转了由多种细菌菌株以及整个 185 个成员群落引起的根部生长的严重抑制。我们证明了 Variovorax 操纵植物激素水平来平衡我们生态上真实的合成根群落对根系生长的影响。我们鉴定了一个生长素降解操纵子，该操纵子在 Variovorax 的所有可用基因组中都是保守的，并且对于根生长抑制的逆转是必要且充分的。因此，代谢信号干扰塑造了细菌-植物通讯网络，对于维持根部的定型发育程序至关重要。优化根际化学相互作用网络的反馈为开发更具弹性和生产力的作物提供了一种有前景的生态策略。在拟南芥根系中使用生态真实的 185 个细菌合成群落进行的实验表明，Variovorax 细菌可以影响植物激素水平，从而逆转群落对根生长的抑制作用。