In situ separation and visualization of synthetic and naturally occurring isomers from heterogeneous plant tissues, especially when they share similar molecular structures, are a challenging task. In this study, we combined the ion mobility separation with desorption electrospray ionization mass spectrometry imaging (DESI-IM-MSI) to achieve a direct separation and visualization of two synthetic auxin derivatives, auxinole and its structural isomer 4pTb-MeIAA, as well as endogenous auxins from Arabidopsis samples. Distinct distribution of these synthetic isomers and endogenous auxins in Arabidopsis primary roots and hypocotyls was achieved in the same imaging analysis from both individually treated and cotreated samples. We also observed putative metabolites of synthetic auxin derivatives, i.e. auxinole amino acid conjugates and hydrolysed 4pTb-MeIAA product - 4pTb-IAA, based on their unique drifting ion intensity patterns. Furthermore, DESI-IM-MSI-revealed abundance of endogenous auxins and synthetic isomers was validated by liquid chromatography-mass spectrometry (LC-MS). Our results demonstrate that DESI-IM-MSI could be used as a robust technique for detecting endogenous and exogenous isomers and provide a spatiotemporal evaluation of hormonomics profiles in plants.

• Keywords
• Auxin, Desorption electrospray ionization, Ion mobility, Isomer, Mass spectrometry imaging, Metabolite,
• MeSH
• Arabidopsis * MeSH
• Spectrometry, Mass, Electrospray Ionization methods   MeSH
• Isomerism MeSH
• Indoleacetic Acids analysis   MeSH
• Molecular Structure MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Indoleacetic Acids MeSH

The field of plant hormonomics focuses on the qualitative and quantitative analysis of the hormone complement in plant samples, akin to other omics sciences. Plant hormones, alongside primary and secondary metabolites, govern vital processes throughout a plant's lifecycle. While active hormones have received significant attention, studying all related compounds provides valuable insights into internal processes. Conventional single-class plant hormone analysis employs thorough sample purification, short analysis and triple quadrupole tandem mass spectrometry. Conversely, comprehensive hormonomics analysis necessitates minimal purification, robust and efficient separation and better-performing mass spectrometry instruments. This review summarizes the current status of plant hormone analysis methods, focusing on sample preparation, advances in chromatographic separation and mass spectrometric detection, including a discussion on internal standard selection and the potential of derivatization. Moreover, current approaches for assessing the spatiotemporal distribution are evaluated. The review touches on the legitimacy of the term plant hormonomics by exploring the current status of methods and outlining possible future trends.

• Keywords
• Hormonomics, Internal standard, Liquid chromatography, Mass spectrometry, Matrix effect, Metabolomics, Omics, Plant hormone, Solid phase extraction,
• Publication type
• Journal Article MeSH
• Review MeSH

The phytohormone auxin is a master regulator of plant growth and development in response to many endogenous and environmental signals. The underlying coordination of growth is mediated by the formation of auxin maxima and concentration gradients. The visualization of auxin dynamics and distribution can therefore provide essential information to increase our understanding of the mechanisms by which auxin orchestrates these growth and developmental processes. Several auxin reporters have been developed to better perceive the auxin distribution and signaling machinery in vivo. This review focuses on different types of auxin reporters and biosensors used to monitor auxin distribution and its dynamics, as well as auxin signaling, at the cellular and tissue levels in different plant species. We provide a brief history of each reporter and biosensor group and explain their principles and utilities.

• MeSH
• Indoleacetic Acids * MeSH
• Plant Growth Regulators * MeSH
• Plants MeSH
• Signal Transduction MeSH
• Plant Development MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Indoleacetic Acids * MeSH
• Plant Growth Regulators * MeSH

The plant nucleus plays an irreplaceable role in cellular control and regulation by auxin (indole-3-acetic acid, IAA) mainly because canonical auxin signaling takes place here. Auxin can enter the nucleus from either the endoplasmic reticulum or cytosol. Therefore, new information about the auxin metabolome (auxinome) in the nucleus can illuminate our understanding of subcellular auxin homeostasis. Different methods of nuclear isolation from various plant tissues have been described previously, but information about auxin metabolite levels in nuclei is still fragmented and insufficient. Herein, we tested several published nucleus isolation protocols based on differential centrifugation or flow cytometry. The optimized sorting protocol leading to promising yield, intactness, and purity was then combined with an ultra-sensitive mass spectrometry analysis. Using this approach, we can present the first complex report on the auxinome of isolated nuclei from cell cultures of Arabidopsis and tobacco. Moreover, our results show dynamic changes in auxin homeostasis at the intranuclear level after treatment of protoplasts with free IAA, or indole as a precursor of auxin biosynthesis. Finally, we can conclude that the methodological procedure combining flow cytometry and mass spectrometry offers new horizons for the study of auxin homeostasis at the subcellular level.

• Keywords
• auxin, auxin metabolism, flow cytometry, nucleus, subcellular fractionation,
• MeSH
• Arabidopsis drug effects   metabolism   ultrastructure   MeSH
• Cell Nucleus drug effects   metabolism   ultrastructure   MeSH
• Cell Culture Techniques MeSH
• Centrifugation methods   MeSH
• Cell Fractionation instrumentation   methods   MeSH
• Mass Spectrometry MeSH
• Homeostasis physiology   MeSH
• Indoles metabolism   pharmacology   MeSH
• Indoleacetic Acids metabolism   MeSH
• Protoplasts chemistry   MeSH
• Flow Cytometry MeSH
• Plant Growth Regulators metabolism   MeSH
• Plant Cells drug effects   metabolism   ultrastructure   MeSH
• Nicotiana drug effects   metabolism   ultrastructure   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• indole MeSH Browser
• Indoles MeSH
• Indoleacetic Acids MeSH
• Plant Growth Regulators MeSH