Tryptophan Levels as a Marker of Auxins and Nitric Oxide Signaling

Abstract

The aromatic amino acid tryptophan is the main precursor for indole-3-acetic acid (IAA), which involves various parallel routes in plants, with indole-3-acetaldoxime (IAOx) being one of the most common intermediates. Auxin signaling is well known to interact with free radical nitric oxide (NO) to perform a more complex effect, including the regulation of root organogenesis and nitrogen nutrition. To fathom the link between IAA and NO, we use a metabolomic approach to analyze the contents of low-molecular-mass molecules in cultured cells of Arabidopsis thaliana after the application of S-nitrosoglutathione (GSNO), an NO donor or IAOx. We separated the crude extracts of the plant cells through ion-exchange columns, and subsequent fractions were analyzed by gas chromatography-mass spectrometry (GC-MS), thus identifying 26 compounds. A principal component analysis (PCA) was performed on N-metabolism-related compounds, as classified by the Kyoto Encyclopedia of Genes and Genomes (KEGG). The differences observed between controls and treatments are mainly explained by the differences in Trp contents, which are much higher in controls. Thus, the Trp is a shared response in both auxin- and NO-mediated signaling, evidencing some common signaling mechanism to both GSNO and IAOx. The differences in the low-molecular-mass-identified compounds between GSNO- and IAOx-treated cells are mainly explained by their concentrations in benzenepropanoic acid, which is highly associated with IAA levels, and salicylic acid, which is related to glutathione. These results show that the contents in Trp can be a marker for the study of auxin and NO signaling.

Polydopamine Modified Carbon Nitride and PAMAM Assembled Electrochemical Immunosensor for Detection of Indole‐3‐Acetic Acid

“…[3] Precise quantification of IAA in plants is critical for enhanced regulation of plant growth and development and development of sustainable agriculture. Quantitative analysis of IAA can be done using various methods, such as high-performance liquid chromatography, [4] gas chromatography-mass spectrometry, [5] capillary electrophoresis, [6] and enzyme linked immunosorbent assay. [7] Nevertheless, these methods are typically costly and time-intensive.…”

Biocompatible Fluorescent Biosensor Reveals the Level and Distribution of Indole-3-Acetic Acid Signals in Plants

“…Methods such as GC-MS, HPLC, LC-MS, and immunoassays have been established to detect IAA in biological samples. − However, these methods usually require expensive scientific instruments, complex data processing systems, and special immunoglobulins, which severely limit their application. Fluorescence analysis is an important tool for trace, ultratrace, or even molecular level analysis, which has the advantages of good selectivity, less sampling, high sensitivity, as well as simplicity and rapidity, and has started to be applied in plant hormone analysis in recent years .…”