4 research outputs found
Mass Spectrometric Imaging of Wheat (Triticum spp.) and Barley (Hordeum vulgare L.) Cultivars: Distribution of Major Cell Wall Polysaccharides According to Their Main Structural Features
Arabinoxylans
(AX) and (1→3),(1→4)-β-glucans
(BG) are the main components of cereal cell walls and influence many
aspects of their end uses. Important variations in the composition
and structure of these polysaccharides have been reported among cereals
and cultivars of a given species. In this work, the spatial distribution
of AX and BG in the endosperm of mature grains was established for
nine wheat varieties and eight barley varieties using enzymatically
assisted mass spectrometry imaging (MSI). Important structural features
of the AX and BG polymers that were previously shown to influence
their physicochemical properties were assessed. Differences in the
distribution of AX and BG structures were observed, both within the
endosperm of a given cultivar and between wheat and barley cultivars.
This study provides a unique picture of the structural heterogeneity
of AX and BG polysaccharides at the scale of the whole endosperm in
a series of wheat and barley cultivars. Thus, it can participate meaningfully
in a strategy aiming at understanding the structure–function
relationships of these two polymers
Expanded Coverage of Phytocompounds by Mass Spectrometry Imaging Using On-Tissue Chemical Derivatization by 4‑APEBA
Probing the entirety of any species metabolome is an
analytical
grand challenge, especially on a cellular scale. Matrix-assisted laser
desorption/ionization mass spectrometry imaging (MALDI-MSI) is a common
spatial metabolomics assay, but this technique has limited molecular
coverage for several reasons. To expand the application space of spatial
metabolomics, we developed an on-tissue chemical derivatization (OTCD)
workflow using 4-APEBA for the confident identification of several
dozen elusive phytocompounds. Overall, this new OTCD method enabled
the annotation of roughly 280 metabolites, with only a 10% overlap
in metabolic coverage when compared to analog negative ion mode MALDI-MSI
on serial sections. We demonstrate that 4-APEBA outperforms other
derivatization agents by providing: (1) broad specificity toward carbonyls,
(2) low background, and (3) introduction of bromine isotopes. Notably,
the latter two attributes also facilitate more confidence in our bioinformatics
for data processing. The workflow detailed here trailblazes a path
toward spatial hormonomics within plant samples, enhancing the detection
of carboxylates, aldehydes, and plausibly other carbonyls. As such,
several phytohormones, which have various roles within stress responses
and cellular communication, can now be spatially profiled, as demonstrated
in poplar root and soybean root nodule
Expanded Coverage of Phytocompounds by Mass Spectrometry Imaging Using On-Tissue Chemical Derivatization by 4‑APEBA
Probing the entirety of any species metabolome is an
analytical
grand challenge, especially on a cellular scale. Matrix-assisted laser
desorption/ionization mass spectrometry imaging (MALDI-MSI) is a common
spatial metabolomics assay, but this technique has limited molecular
coverage for several reasons. To expand the application space of spatial
metabolomics, we developed an on-tissue chemical derivatization (OTCD)
workflow using 4-APEBA for the confident identification of several
dozen elusive phytocompounds. Overall, this new OTCD method enabled
the annotation of roughly 280 metabolites, with only a 10% overlap
in metabolic coverage when compared to analog negative ion mode MALDI-MSI
on serial sections. We demonstrate that 4-APEBA outperforms other
derivatization agents by providing: (1) broad specificity toward carbonyls,
(2) low background, and (3) introduction of bromine isotopes. Notably,
the latter two attributes also facilitate more confidence in our bioinformatics
for data processing. The workflow detailed here trailblazes a path
toward spatial hormonomics within plant samples, enhancing the detection
of carboxylates, aldehydes, and plausibly other carbonyls. As such,
several phytohormones, which have various roles within stress responses
and cellular communication, can now be spatially profiled, as demonstrated
in poplar root and soybean root nodule
Multimodal MSI in Conjunction with Broad Coverage Spatially Resolved MS<sup>2</sup> Increases Confidence in Both Molecular Identification and Localization
One critical aspect
of mass spectrometry imaging (MSI) is the need
to confidently identify detected analytes. While orthogonal tandem
MS (e.g., LC–MS<sup>2</sup>) experiments from sample extracts
can assist in annotating ions, the spatial information about these
molecules is lost. Accordingly, this could cause mislead conclusions,
especially in cases where isobaric species exhibit different distributions
within a sample. In this Technical Note, we employed a multimodal
imaging approach, using matrix assisted laser desorption/ionization
(MALDI)-MSI and liquid extraction surface analysis (LESA)-MS<sup>2</sup>I, to confidently annotate and localize a broad range of metabolites
involved in a tripartite symbiosis system of moss, cyanobacteria,
and fungus. We found that the combination of these two imaging modalities
generated very congruent ion images, providing the link between highly
accurate structural information onfered by LESA and high spatial resolution
attainable by MALDI. These results demonstrate how this combined methodology
could be very useful in differentiating metabolite routes in complex
systems