Department for Biochemistry, Max Planck Institute for Chemical Ecology, Jena, Germany.
Department of Mass Spectrometry and Metabolomics, Max Planck Institute for Chemical Ecology, Jena, Germany.
Physiol Plant. 2023 Nov-Dec;175(6):e14078. doi: 10.1111/ppl.14078.
Aromatic aldehydes and amines are common plant metabolites involved in several specialized metabolite biosynthesis pathways. Recently, we showed that the aromatic aldehyde synthase PtAAS1 and the aromatic amino acid decarboxylase PtAADC1 contribute to the herbivory-induced formation of volatile 2-phenylethanol and its glucoside 2-phenylethyl-β-D-glucopyranoside in Populus trichocarpa. To unravel alternative metabolic fates of phenylacetaldehyde and 2-phenylethylamine beyond alcohol and alcohol glucoside formation, we heterologously expressed PtAAS1 and PtAADC1 in Nicotiana benthamiana and analyzed plant extracts using untargeted LC-qTOF-MS and targeted LC-MS/MS analysis. While the metabolomes of PtAADC1-expressing plants did not significantly differ from those of control plants, expression of PtAAS1 resulted in the accumulation of phenylacetic acid (PAA) and PAA-amino acid conjugates, identified as PAA-aspartate and PAA-glutamate. Herbivory-damaged poplar leaves revealed significantly induced accumulation of PAA-Asp, while levels of PAA remained unaltered upon herbivory. Transcriptome analysis showed that members of auxin-amido synthetase GH3 genes involved in the conjugation of auxins with amino acids were significantly upregulated upon herbivory in P. trichocarpa leaves. Overall, our data indicates that phenylacetaldehyde generated by poplar PtAAS1 serves as a hub metabolite linking the biosynthesis of volatile, non-volatile herbivory-induced specialized metabolites, and phytohormones, suggesting that plant growth and defense can be balanced on a metabolic level.
芳香醛和胺是参与几种特殊代谢物生物合成途径的常见植物代谢物。最近，我们表明芳香醛合酶 PtAAS1 和芳香族氨基酸脱羧酶 PtAADC1 有助于诱导杨属植物中挥发性 2-苯乙醇及其糖苷 2-苯乙基-β-D-吡喃葡萄糖苷的形成。为了揭示苯乙醛和 2-苯乙胺除了形成醇和醇糖苷之外的替代代谢命运，我们在烟草中异源表达了 PtAAS1 和 PtAADC1，并使用非靶向 LC-qTOF-MS 和靶向 LC-MS/MS 分析来分析植物提取物。虽然 PtAADC1 表达植物的代谢组没有显着不同于对照植物，但 PtAAS1 的表达导致苯乙酸 (PAA) 和 PAA-氨基酸缀合物的积累，鉴定为 PAA-天冬氨酸和 PAA-谷氨酸。受损的杨树叶片显示出 PAA-Asp 的明显诱导积累，而在受到草食动物侵害时 PAA 的水平没有变化。转录组分析表明，在杨树叶片中，参与将生长素与氨基酸缀合的生长素酰胺合成酶 GH3 基因的成员在受到草食动物侵害时显着上调。总的来说，我们的数据表明，杨树 PtAAS1 产生的苯乙醛作为一个枢纽代谢物，将挥发性、非挥发性草食动物诱导的特殊代谢物和植物激素的生物合成联系起来，这表明植物的生长和防御可以在代谢水平上达到平衡。
