Climate warming can influence interactions between plants and associated organisms by altering levels of plant secondary metabolites. In contrast to studies of elevated temperature on aboveground phytochemistry, the consequences of warming on root chemistry have received little attention. Herein, we investigated the effects of elevated temperature, defoliation, and genotype on root biomass and phenolic compounds in trembling aspen (Populus tremuloides). We grew saplings of three aspen genotypes under ambient or elevated temperatures (+4–6 °C), and defoliated (by 75%) half of the trees in each treatment. After 4 months, we harvested roots and determined their condensed tannin and salicinoid (phenolic glycoside) concentrations. Defoliation reduced root biomass, with a slightly larger impact under elevated, relative to ambient, temperature. Elevated temperature decreased condensed tannin concentrations by 21–43% across the various treatment combinations. Warming alone did not alter salicinoid concentrations but eliminated a small negative impact of defoliation on those compounds. Graphical vector analysis suggests that effects of warming and defoliation on condensed tannins and salicinoids were predominantly due to reduced biosynthesis of these metabolites in roots, rather than to changes in root biomass. In general, genotypes did not differ in their responses to temperature or temperature by defoliation interactions. Collectively, our results suggest that future climate warming will alter root phytochemistry, and that effects will vary among different classes of secondary metabolites and be influenced by concurrent ecological interactions such as herbivory. Temperature- and herbivory-mediated changes in root chemistry have the potential to influence belowground trophic interactions and soil nutrient dynamics.

气候变暖可以通过改变植物次生代谢产物的水平来影响植物与相关生物之间的相互作用。与地上植物化学升高的温度研究相反，变暖对根化学的影响很少引起关注。在这里，我们调查了高温，落叶和基因型对颤抖的白杨（杨杨）根生物量和酚类化合物的影响）。我们在环境温度或升高的温度下（+ 4–6°C）种植了三种基因型的白杨树苗，每次处理都使一半的树脱叶（增加75％）。4个月后，我们收获了根，并确定了它们的单宁和水杨素（酚类糖苷）的浓缩浓度。脱叶减少了根生物量，在相对于环境温度升高的情况下影响更大。在各种处理组合中，升高的温度可使单宁冷凝的浓度降低21–43％。单独加热不会改变水杨素的浓度，但消除了落叶对这些化合物的负面影响。图形矢量分析表明，升温和脱叶对单宁浓缩和水杨素的影响主要是由于这些代谢产物在根部的生物合成减少，而不是改变根系生物量。通常，基因型对温度的反应或通过脱叶相互作用对温度的反应没有差异。总体而言，我们的结果表明，未来的气候变暖将改变根的植物化学，其影响将在不同类别的次生代谢产物之间变化，并受到同时发生的生态相互作用（如草食动物）的影响。温度和食草生物介导的根系化学变化可能会影响地下的营养相互作用和土壤养分动态。而且这种影响在不同类别的次生代谢产物之间会有所不同，并会受到同时发生的生态相互作用（例如草食动物）的影响。温度和食草生物介导的根系化学变化可能会影响地下的营养相互作用和土壤养分动态。而且这种影响在不同类别的次生代谢产物之间会有所不同，并会受到同时发生的生态相互作用（例如草食动物）的影响。温度和食草生物介导的根系化学变化可能会影响地下的营养相互作用和土壤养分动态。