Metabolomics approach to investigate phytotoxic effects of <i>Wedelia trilobata</i> leaves, litter and soil

Although release and accumulation of plant metabolites from plant into soil can influence allelopathy, little information is known about metabolite changes that occur in leaf, litter and soil. In this study, seed germination bioassay tests and metabolomics analysis were performed to investigate the phytotoxic effects and metabolic variations (measured as buckets) in the ethanolic extracts of leaf, leaf litter and soil of <i>Wedelia trilobata</i>. Increasing the ethanolic extracts concentration of all extracts significantly inhibited <i>Lactuca sativa</i> germination rate (GR), shoot height (SH) and root length (RL). Soil exerted the strongest inhibition but contained the lowest number of buckets relative to those of leaf and leaf litter extracts. An overlap overview on the metabolome revealed a poor bucket overlap and redundancy among the leaf, leaf litter and soil extracts. Canonical correspondence analysis concluded that the SH of <i>L. sativa</i> was more sensitive to leaf litter extract and the leaf extract exerted a strong influence on the GR and RL of <i>L. sativa</i>. Multivariate analysis suggested that the metabolome of the leaf, leaf litter and soil differ substantially. Finally, putative identification using MS/MS data demonstrated various plant metabolites with phytotoxic effects that can contribute to the allelopathy of <i>W. trilobata</i>.

尽管植物代谢物从植物体释放并累积至土壤的过程可影响化感作用，但目前针对叶、枯落物及土壤中代谢物变化的相关研究仍较为匮乏。本研究通过种子萌发生物测定试验与代谢组学分析，探究了三裂蟛蜞菊（Wedelia trilobata）的叶、叶枯落物及土壤乙醇提取物的植物毒性效应，以及其中的代谢变异情况（以特征峰桶（buckets）计）。提升各提取物的乙醇提取液浓度后，莴苣（Lactuca sativa）的发芽率（germination rate, GR）、株高（shoot height, SH）及根长（root length, RL）均受到显著抑制。土壤提取物表现出最强的抑制效果，但其所含的特征峰桶数量相较于叶提取物与叶枯落物提取物最少。代谢组重叠分析结果显示，叶、叶枯落物与土壤提取物之间的特征峰桶重叠度较低，且存在冗余现象。典范对应分析结果表明，莴苣的株高对叶枯落物提取物更为敏感，而叶提取物则对莴苣的发芽率与根长具有显著影响。多变量分析结果显示，叶、叶枯落物及土壤的代谢组存在显著差异。最终，基于串联质谱（MS/MS）数据的推定鉴定结果显示，多种具有植物毒性的植物代谢物可参与三裂蟛蜞菊（W. trilobata）的化感作用过程。