Use of ultraviolet laser ablation electrospray ionization mass spectrometry for plant metabolite imaging

This dissertation describes a variety of plant studies by laser ablation electrospray ionization mass spectrometry imaging. (LAESI MSI). During the LAESI process, a plant sample is ablated when a laser is fired at it. The resultant neutral plume is ionized and enters the mass spectrometer by an electrospray stream. In all experiments an ultraviolet (UV; 355 Nd:YAG) laser was used. Once ions enter the mass spectrometer and are detected, a spectrum is produced for a particular area on the plant. The rest of the plant is ablated and spectra are combined for image creation. Unlike other forms of mass spectrometry, MSI allows for chemical and spatial information which can help understand the diversity of plants, where one cell may contain different chemicals compared to its neighboring cell. Plants studied in this dissertation included peonies, coleus, and Arabidopsis thaliana. A variety of metabolites were imaged, including flavonoids, anthocyanins and lipids. Analyte images allowed further insight into biological processes, such as the malonylshisonin pathway in coleus leaves, and effects of lipids during autophagy in Arabidopsis thaliana. LAESI MSI was also shown in this dissertation to be a potentially faster more sensitive technique than other forms of mass spectrometry

Light-Dependent Changes in the Spatial Localization of Metabolites in Solenostemon scutellarioides (Coleus Henna) Visualized by Matrix-Free Atmospheric Pressure Electrospray Laser Desorption Ionization Mass Spectrometry Imaging

The visualization of foliage color in plants provides immediate insight into some of the compounds that exist in the leaf. However, many non-colored compounds are also present; their cellular distributions are not readily identifiable optically. In this study we evaluate the applicability of mass spectrometry imaging (MSI) via electrospray laser desorption ionization (ELDI) to reveal the spatial distribution of metabolites. ELDI-MSI is a matrix free, atmospheric pressure ionization method that utilizes a UV laser coupled with supplemental ionization by electrospray. We specifically applied ELDI-MSI to determine the spatial distribution of metabolites in Coleus Henna half leaves that were grown with half-sections either fully illuminated or shaded. We monitored dynamic changes in the spatial distribution of metabolites in response to the change of illumination every 7 days for a 28 day period. A novel source-sink relationship was observed between the 2 halves of the experimental leaf. Furthermore, Coleus Henna leaves present visually recognizable sectors associated with the differential accumulation of flavonoids. Thus, we correlated the effect of differential illumination and presence or absence of flavonoids with metabolic changes revealed by the accumulation of carbohydrates, amino acids, and organic acids. The results show the potential of ELDI-MSI to provide spatial information for a variety of plant metabolites with little sample preparation

Use of ultraviolet laser ablation electrospray ionization mass spectrometry for plant metabolite imaging

This dissertation describes a variety of plant studies by laser ablation electrospray ionization mass spectrometry imaging. (LAESI MSI). During the LAESI process, a plant sample is ablated when a laser is fired at it. The resultant neutral plume is ionized and enters the mass spectrometer by an electrospray stream. In all experiments an ultraviolet (UV; 355 Nd:YAG) laser was used. Once ions enter the mass spectrometer and are detected, a spectrum is produced for a particular area on the plant. The rest of the plant is ablated and spectra are combined for image creation. Unlike other forms of mass spectrometry, MSI allows for chemical and spatial information which can help understand the diversity of plants, where one cell may contain different chemicals compared to its neighboring cell. Plants studied in this dissertation included peonies, coleus, and Arabidopsis thaliana. A variety of metabolites were imaged, including flavonoids, anthocyanins and lipids. Analyte images allowed further insight into biological processes, such as the malonylshisonin pathway in coleus leaves, and effects of lipids during autophagy in Arabidopsis thaliana. LAESI MSI was also shown in this dissertation to be a potentially faster more sensitive technique than other forms of mass spectrometry.</p

Light-Dependent Changes in the Spatial Localization of Metabolites in Solenostemon scutellarioides (Coleus Henna) Visualized by Matrix-Free Atmospheric Pressure Electrospray Laser Desorption Ionization Mass Spectrometry Imaging

The visualization of foliage color in plants provides immediate insight into some of the compounds that exist in the leaf. However, many non-colored compounds are also present; their cellular distributions are not readily identifiable optically. In this study we evaluate the applicability of mass spectrometry imaging (MSI) via electrospray laser desorption ionization (ELDI) to reveal the spatial distribution of metabolites. ELDI-MSI is a matrix free, atmospheric pressure ionization method that utilizes a UV laser coupled with supplemental ionization by electrospray. We specifically applied ELDI-MSI to determine the spatial distribution of metabolites in Coleus Henna half leaves that were grown with half-sections either fully illuminated or shaded. We monitored dynamic changes in the spatial distribution of metabolites in response to the change of illumination every 7 days for a 28 day period. A novel source-sink relationship was observed between the 2 halves of the experimental leaf. Furthermore, Coleus Henna leaves present visually recognizable sectors associated with the differential accumulation of flavonoids. Thus, we correlated the effect of differential illumination and presence or absence of flavonoids with metabolic changes revealed by the accumulation of carbohydrates, amino acids, and organic acids. The results show the potential of ELDI-MSI to provide spatial information for a variety of plant metabolites with little sample preparation.</p

Light-Dependent Changes in the Spatial Localization of Metabolites in Solenostemon scutellarioides (Coleus Henna) Visualized by Matrix-Free Atmospheric Pressure Electrospray Laser Desorption Ionization Mass Spectrometry Imaging

The visualization of foliage color in plants provides immediate insight into some of the compounds that exist in the leaf. However, many non-colored compounds are also present; their cellular distributions are not readily identifiable optically. In this study we evaluate the applicability of mass spectrometry imaging (MSI) via electrospray laser desorption ionization (ELDI) to reveal the spatial distribution of metabolites. ELDI-MSI is a matrix free, atmospheric pressure ionization method that utilizes a UV laser coupled with supplemental ionization by electrospray. We specifically applied ELDI-MSI to determine the spatial distribution of metabolites in Coleus Henna half leaves that were grown with half-sections either fully illuminated or shaded. We monitored dynamic changes in the spatial distribution of metabolites in response to the change of illumination every 7 days for a 28 day period. A novel source-sink relationship was observed between the 2 halves of the experimental leaf. Furthermore, Coleus Henna leaves present visually recognizable sectors associated with the differential accumulation of flavonoids. Thus, we correlated the effect of differential illumination and presence or absence of flavonoids with metabolic changes revealed by the accumulation of carbohydrates, amino acids, and organic acids. The results show the potential of ELDI-MSI to provide spatial information for a variety of plant metabolites with little sample preparation