Plant defense chemistry is often hypothesized to drive ecological and evolutionary success in diverse tropical forests, yet detailed characterizations of plant secondary metabolites in tropical plants are logistically challenging. Here, we explore a new integrative approach that combines visible‐to‐shortwave infrared (VSWIR) spectral reflectance data with detailed plant metabolomics data from 19 Protium (Burseraceae) tree species. Building on the discovery that different Protium species have unique chemistries yet share many secondary metabolites, we devised a method to test for associations between metabolites and VSWIR spectral data. Given species‐level variation in metabolite abundance, we correlated the concentration of particular chemicals with the reflectance of the spectral bands in a wavelength band per secondary metabolite matrix. We included 45 metabolites that were shared by at least 5 Protium species and correlated their per‐species foliar abundances against each one of 210 wavelength bands of field‐measured VSWIR spectra. Finally, we tested whether classes of similar metabolites showed similar relationships with spectral patterns. We found that many secondary metabolites yielded strong correlations with VSWIR spectra of Protium. Furthermore, important Protium metabolite classes such as procyanidins (condensed tannins) and phytosterols were grouped together in a hierarchical clustering analysis (Ward’s algorithm), confirming similarity in their associations with plant spectral patterns. We also found a significant correlation in the phenolics content between juvenile and canopy trees of the same species, suggesting that species‐level variation in defense chemistry is consistent across life stages and geographic distribution. We conclude that the integration of spectral and metabolic approaches could represent a powerful and economical method to characterize important aspects of tropical plant defense chemistry.

中文翻译：

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探索亚马孙树木不同属次生代谢产物与叶片光谱反射率之间的联系

人们常以植物防御化学为基础，在不同的热带森林中推动生态和进化的成功，但是对热带植物中植物次生代谢产物的详细表征在逻辑上存在挑战。在这里，我们探索了一种新的整合方法，该方法将可见光至短波红外（VSWIR）光谱反射率数据与来自19个Pro属（Burseraceae）树种的详细植物代谢组学数据相结合。基于发现不同的Protium物种具有独特的化学性质，但共有许多次生代谢物，我们设计了一种方法来测试代谢物与VSWIR光谱数据之间的关联。给定代谢物丰度的物种水平变化，我们将特定化学物质的浓度与每个次生代谢物基质的波长带中光谱带的反射率相关联。我们纳入了至少5个Pro物种共有的45种代谢物，并将其每种物种的叶片丰度与现场测量的VSWIR光谱的210个波长带中的每一个相关。最后，我们测试了相似代谢物的类别是否与光谱模式显示出相似的关系。我们发现，很多次级代谢产物产生了很强的相关性与VSWIR光谱氕。此外，重要的Pro代谢产物类别（如原花青素（缩合单宁）和植物甾醇）在分级聚类分析（Ward算法）中分组在一起，从而确认了它们与植物光谱模式的相似性。我们还发现同一物种的幼树和冠层树之间的酚含量之间存在显着相关性，这表明防御化学的物种水平差异在整个生命阶段和地理分布上是一致的。我们得出的结论是，光谱和代谢方法的整合可能代表了表征热带植物防御化学重要方面的一种强大而经济的方法。