PDF(Pubmed)
Abstract：
Herbivory can be reduced by the production of defense compounds (secondary metabolites), but generally defenses are costly, and growth is prioritized over defense. While defense compounds may deter herbivory, nutrients may promote it. In a field study in boreal forest in Norway, we investigated how simulated herbivory affected concentrations of phenolics (generally a defense) and the carbon/nitrogen (C/N) ratio in annual shoots of bilberry (Vaccinium myrtillus), a deciduous clonal dwarf shrub whose vegetative and generative parts provide forage for many boreal forest animals. We measured concentrations of total tannins, individual phenolics, nitrogen and carbon following several types and intensities of herbivory. We identified 22 phenolics: 15 flavonoids, 1 hydroquinone and 6 phenolic acids. After high levels of herbivory, the total tannin concentration and the concentration of these 22 phenolics together (called total phenolic concentration) were significantly lower in bilberry annual shoots than in the control (natural herbivory at low to intermediate levels). Low-intensive herbivory, including severe defoliation, gave no significantly different total tannin or total phenolic concentration compared with the control. Many individual phenolics followed this pattern, while phenolic acids (deterring insect herbivory) showed little response to the treatments: their concentrations were maintained after both low-intensive and severe herbivory. Contrary to our predictions, we found no significant difference in C/N ratio between treatments. Neither the Carbon:Nutrient Balance hypothesis nor the Optimal Defense hypotheses, theories predicting plant resource allocation to secondary compounds, can be used to predict changes in phenolic concentrations (including total tannin concentration) in bilberry annual shoots after herbivory: in this situation, carbon is primarily used for other functions (e.g., maintenance, growth, reproduction) than defense.
摘要：
草食性可以通过防御化合物（次生代谢产物）的产生来减少，但是一般来说防御是昂贵的，增长优先于国防。虽然防御化合物可能会阻止食草动物，营养素可以促进它。在挪威北方森林的实地研究中，我们调查了模拟草食性如何影响越橘（越橘）的年度芽中酚类物质（通常是防御）和碳/氮（C/N）比的浓度，一种落叶无性系矮灌木，其植物和生殖部分为许多北方森林动物提供饲料。我们测量了总单宁的浓度，个别酚类物质，氮和碳遵循几种类型和强度的食草动物。我们鉴定了22种酚类物质：15种类黄酮，1的对苯二酚和6的酚酸。经过高水平的食草动物，越橘一年生芽的总单宁浓度和这22种酚类物质的浓度（称为总酚浓度）显着低于对照（低至中等水平的天然食草动物）。低密集食草动物，包括严重的落叶,与对照相比，没有显着差异的总单宁或总酚浓度。许多单独的酚类物质遵循这种模式，虽然酚酸（阻止昆虫食草动物）对治疗的反应很小：在低强度和严重食草动物之后，它们的浓度得以维持。与我们的预测相反,我们发现处理之间的C/N比没有显着差异。无论是碳：营养平衡假说还是最优防御假说，预测植物资源分配到次生化合物的理论，可用于预测草食后越橘年芽中酚类浓度（包括总单宁浓度）的变化：在这种情况下，碳主要用于其他功能(例如，维护,增长,复制)而不是防御。
