Department of Animal and Grassland Sciences, University of Miyazaki, Miyazaki, Japan.
PLoS One. 2021 Feb 18;16(2):e0247276. doi: 10.1371/journal.pone.0247276. eCollection 2021.
Plant hormones have been identified to be versatile signaling molecules essential for plant growth, development, and stress response. Their content levels vary depending on the species, and they also change in response to any external stimuli. Thus, simultaneous quantification of multiple plant hormones is required to understand plant physiology. Sensitive and quantitative analysis using liquid chromatography-linked mass spectrometry (LC-MS/MS) has been used in detecting plant hormones; however, quantification without stable isotopes is yet to be established. In this study, we quantified seven representative plant hormones of Lotus japonicus, which is a model legume for standard addition method. Accurate masses for monoisotopic ions of seven phytohormones were determined for high-resolution mass spectrometry (HR-MS). Selected ion monitoring (SIM) mode based on accurate masses was used in detecting phytohormones in the roots, stems, and leaves. Evaluation of matrix effects showed ion suppression ranging from 10.2% to 87.3%. Both stable isotope dilution and standard addition methods were able to detect plant hormones in the roots, stems, and leaves, with no significant differences in using both approaches and thus a standard addition method can be used to quantify phytohormones in L. japonicus. The method will be effective, especially when stable isotopes are not available to correct for matrix effects.
植物激素已被确定为多功能信号分子，对于植物的生长、发育和应激反应至关重要。它们的含量水平因物种而异，也会对外界刺激做出反应而发生变化。因此，需要同时定量分析多种植物激素，才能了解植物的生理机能。液相色谱-串联质谱（LC-MS/MS）技术已被用于检测植物激素；然而，在没有稳定同位素的情况下进行定量分析仍有待建立。在这项研究中，我们对作为标准添加法定量方法模型的模式豆科植物——日本田七，进行了七种代表性植物激素的定量分析。使用高分辨率质谱（HR-MS）确定了七种植物激素的单同位素离子精确质量。基于精确质量的选择离子监测（SIM）模式用于检测根、茎和叶中的植物激素。基质效应的评估表明，离子抑制范围为 10.2%至 87.3%。稳定同位素稀释法和标准添加法都能够检测到根、茎和叶中的植物激素，两种方法的检测结果没有显著差异，因此可以使用标准添加法来定量日本田七中的植物激素。该方法尤其在无法使用稳定同位素来校正基质效应时非常有效。
