Plant-microbial-soil interactions are key to understanding plant community succession, invasion success, patterns of biodiversity and aspects of ecosystem function. Yet root and rhizosphere chemistry is highly complex, and little is known about natural variation across environmental gradients. Variation in tree species root chemical phenotypes should alter how rhizosphere microbes respond, showing a plant conditioning effect on the chemical makeup of the soil. Here, we used metabolomics to assess bulk small molecule profiles addressing the hypothesis that genetic variation across a species range would result in varying metabolic profiles in roots and surrounding soil. Using UPLC-HRMS we assessed the small molecule profile of root tissue and surrounding rhizosphere soil from 5-year old plant clones collected from six populations of Populus angustifolia across the western U.S., grown in a common environment. Population-level variation was found in over 12,000 root metabolomes and over 5000 soil organic compounds across the populations. Redundancy analysis of over twelve thousand metabolites suggests that plant population origin can account for up to 36% of the variation in roots and 30% of the variation in rhizosphere soil chemistry. Co-inertia analysis indicates that variation in root metabolite profiles explains 15% of the variation in paired soil samples. Distinct populations have evolved different root tissue metabolomes. The difference in root metabolites across populations altered the rhizosphere soil composition, creating variable soil chemical communities from a homogenous starting condition. This suggests that intra-specific plant conditioning of soil varies by plant population.

中文翻译：

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Populus angustifolia 种群已经进化出影响其周围土壤的不同代谢特征

植物-微生物-土壤相互作用是了解植物群落演替、入侵成功、生物多样性模式和生态系统功能方面的关键。然而，根和根际化学非常复杂，人们对环境梯度的自然变化知之甚少。树种根系化学表型的变化应该会改变根际微生物的反应方式，显示出植物对土壤化学成分的调节作用。在这里，我们使用代谢组学来评估大量小分子谱，解决了物种范围内的遗传变异会导致根和周围土壤中不同的代谢谱的假设。我们使用 UPLC-HRMS 评估了根组织和周围根际土壤的小分子概况，这些数据来自从美国西部六个种植在共同环境中的杨树种群中收集的 5 年生植物克隆。在超过 12,000 种根代谢组和超过 5000 种土壤有机化合物中发现了种群水平的变异。超过 1.2 万种代谢物的冗余分析表明，植物种群起源可以解释多达 36% 的根变异和 30% 的根际土壤化学变异。共惯性分析表明，根代谢物谱的变化解释了配对土壤样品中 15% 的变化。不同的种群进化出不同的根组织代谢组。不同种群根系代谢物的差异改变了根际土壤组成，从同质的起始条件产生了可变的土壤化学群落。这表明土壤的种内植物调节因植物种群而异。