Identification and Structural Elucidation of Acylsugars in Tomato Leaves Using Liquid Chromatography–Ion Mobility–Tandem Mass Spectrometry (LC-IM-MS/MS)

Leaves of tomato plants contain various glandular trichomes that produce a wide range of metabolic products including acylsugars, which may serve as a defense mechanism against various insect pests. Acylsugars exhibit significant structural diversity, differing in their sugar cores, acylated positions, and type of acyl chains. This work demonstrated a comprehensive approach using multidimensional separation techniques, specifically liquid chromatography–ion mobility–tandem mass spectrometry (LC-IM-MS/MS), for structural characterization, and the discrimination of different tomato plants (one cultivar and five accessions) was demonstrated using tomato leaf extracts; six genotypes from five species of Solanum were represented. As a result, we identified 16 acylsugars through their molecular formulas and annotations using LC and MS analyses. The incorporation of ion mobility (IM) analysis revealed an additional 9 isomeric forms, resulting in a comprehensive total of 25 isomeric acylsugars identified. Furthermore, the experimental collision cross section (CCSexp) values agreed reasonably well with the corresponding predicted values (CCSpred), with an overall estimated error of less than 2%. These findings pave the way for research into how the different structural isomers of acylsugars might influence the self-defense mechanism in plants. Moreover, this work demonstrated that the investigated cultivar and accessions of tomatoes can be distinguished from each other based on their metabolite profile, e.g., acylsugars, with principal component analysis (PCA) and linear discriminant analysis (LDA) statistical models, yielding a prediction rate of 98.3%.番茄植株叶片含有多种腺毛，可产生包括酰基糖（acylsugars）在内的多种代谢产物，这类物质可能作为抵御多种昆虫虫害的防御机制。酰基糖具有显著的结构多样性，其差异体现在糖核心、酰化位点以及酰基链类型上。本研究提出了一套采用多维分离技术的系统性分析方案，具体为液相色谱-离子迁移谱-串联质谱（LC-IM-MS/MS），用于结构表征，并通过番茄叶片提取物实现了对不同番茄植株（1个栽培品种与5份种质资源）的鉴别；本次研究涵盖茄属（Solanum）5个物种的6个基因型。最终，通过液相色谱与质谱分析得到的分子式及注释信息，我们成功鉴定出16种酰基糖。引入离子迁移谱（IM）分析后，额外检出9种同分异构体，最终共计鉴定得到25种带有同分异构结构的酰基糖。实验测得的碰撞截面积（CCSexp）与对应预测值（CCSpred）吻合度良好，整体估算误差小于2%。上述研究结果为探究酰基糖不同结构异构体如何影响植物自身防御机制的相关研究铺平了道路。此外，本研究证实，借助主成分分析（PCA）与线性判别分析（LDA）统计模型，可基于代谢物谱（如酰基糖）区分本次研究涉及的番茄栽培品种与种质资源，预测准确率达98.3%。