Plant roots nurture a wide variety of microbes via exudation of metabolites, shaping the rhizosphere's microbial community. Despite the importance of plant specialized metabolites in the assemblage and function of microbial communities in the rhizosphere, little is known of how far the effects of these metabolites extend through the soil. We employed a fluid model to simulate the spatiotemporal distribution of daidzein, an isoflavone secreted from soybean roots, and validated using soybeans grown in a rhizobox. We then analysed how daidzein affects bacterial communities using soils artificially treated with daidzein. Simulation of daidzein distribution showed that it was only present within a few millimetres of root surfaces. After 14 days in a rhizobox, daidzein was only present within 2 mm of root surfaces. Soils with different concentrations of daidzein showed different community composition, with reduced α-diversity in daidzein-treated soils. Bacterial communities of daidzein-treated soils were closer to those of the soybean rhizosphere than those of bulk soils. This study highlighted the limited distribution of daidzein within a few millimetres of root surfaces and demonstrated a novel role of daidzein in assembling bacterial communities in the rhizosphere by acting as more of a repellant than an attractant.

中文翻译：

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根际模型揭示了大豆苷元塑造大豆根际细菌群落的时空分布。

植物根部通过代谢物的分泌来培育各种微生物，从而塑造了根际的微生物群落。尽管植物专用代谢物在根际微生物群落的组成和功能中具有重要意义，但人们对这些代谢物在土壤中的延伸范围知之甚少。我们采用流体模型模拟大豆黄酮（大豆根部分泌的异黄酮）的时空分布，并使用在根瘤菌箱中生长的大豆进行了验证。然后，我们分析了使用大豆苷元人工处理过的土壤中大豆苷元如何影响细菌群落。大豆苷元分布的模拟表明，它仅存在于根表面的几毫米内。在根瘤菌箱中放置14天后，黄豆苷元仅存在于根部表面2 mm以内。大豆苷元浓度不同的土壤表现出不同的群落组成，在大豆苷元处理的土壤中其α多样性降低。大豆苷元处理土壤的细菌群落比散装土壤的细菌群落更靠近大豆根际。这项研究突显了大豆苷元在根表面几毫米内的有限分布，并证明了大豆苷元在根际中组装细菌群落的新作用，它起着驱避剂的作用而不是引诱剂的作用。