生长于不同食性昆虫胁迫下的植物地理种群可能进化出不同的化学防御策略(质量防御和数量防御)。入侵植物在原产地同时受到专食性和广食性昆虫的胁迫，而在入侵地则往往"逃逸"了专食性昆虫，仅受广食性昆虫的取食，这为研究植物化学防御策略的适应性进化提供了绝佳的实验材料。本项目以原产于中国，现在北美成功入侵的大戟科植物乌桕为研究对象，选用遗传背景明确的入侵地乔治亚、德克萨斯种群和原产地广东、江苏种群，采用以核磁共振和液相色谱-质谱为分析手段的代谢组学方法全面分析乌桕的次生代谢产物，通过生物信息学分析不同种群次生代谢产物的差异，同时结合生物测定检测次生代谢产物对专食性昆虫和广食性昆虫生长和繁殖的影响，最终明确主要抗性物质及其质量防御和数量防御作用。研究结果有助于揭示生长于不同昆虫胁迫下的植物地理种群化学防御策略适应性进化的方向和趋势，并对阐明入侵植物的入侵机制以及开展合理有效的生物防治措施均有重要意义。

Selection on defense strategies (qualitative vs. quantitative defense) may be inconsistent in direction and magnitude between sites because of changes in the herbivores community context (specialist vs. generalist) in which the plant population is embedded. This may be the case for some invasive species, which are often introduced without coevolved specialists, but suffer generalist damage comparable to their native ranges. Here, we will examine adaptive evolution of chemical defense strategies using invasive plant species Chinese tallow (Triadica sebifera). In this study, we will compare invasive population (Georgia and Texas, US) and its source population (Guangdong and Jiangsu, China) based on microsatellite markers. We will conduct nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS) to investigate the secondary chemicals, on which principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) will be applied to explore chemical differentiation between plant populations. Then, we will use bioassay with both specialist and generalist to identify the qualitative and quantitative defense. The results will elucidate the evolutionary direction and magnitude of chemical defensive strategies under different herbivore selection. Moreover, this study will provide new and broader insights into understanding invasive plant defense mechanisms and have important implications for biological control.