investigation-xenobiotics-metabolism-salix-alba-leaves-via-mass

Investigation of Xenobiotics Metabolism In <em>Salix alba</em> Leaves via Mass Spectrometry Imaging

The method presented uses mass spectrometry imaging (MSI) to establish the metabolic profile of S. alba leaves when exposed to xenobiotics. Using a ...

université de strasbourg

Here we have examined the composition of free sterols and steryl esters of pollen from selected angiosperm species, as a first step towards a comprehensive analysis of sterol biogenesis in the male gametophyte. We detected four major sterol structural groups: cycloartenol derivatives bearing a 9β,19-cyclopropyl group, sterols with a double bond at C-7(8), sterols with a double bond at C-5(6), and stanols. All these groups were unequally distributed among species. However, the distribution of sterols as free sterols or as steryl esters in pollen grains indicated that free sterols were mostly Δ(5)-sterols and that steryl esters were predominantly 9β,19-cyclopropyl sterols. In order to link the sterol composition of a pollen grain at anthesis with the requirement for membrane lipid constituents of the pollen tube, we germinated pollen grains from Nicotiana tabacum, a model plant in reproductive biology. In the presence of radiolabelled mevalonic acid and in a time course series of measurements, we showed that cycloeucalenol was identified as the major neosynthesized sterol. Furthermore, the inhibition of cycloeucalenol neosynthesis by squalestatin was in full agreement with a de novo biogenesis and an apparent truncated pathway in the pollen tube. 

Plant Sterol Diversity in Pollen from Angiosperms.

Barley (Hordeum vulgare) is the fourth crop cultivated in the world for human consumption and animal feed, making it important to breed healthy and productive plants. Among the threats for barley are lodging, diseases, and pathogens. To avoid lodging, dwarf and semi-dwarf mutants have been selected through breeding processes. Most of these mutants are affected on hormonal biosynthesis or signalling. Here, we present the metabolic characterization of a brassinosteroid insensitive semi-dwarf mutant, BW312. The hormone profile was determined through a targeted metabolomics analysis by UHPLC-triple quadrupole-MS/MS, showing an induction of gibberellic acid and jasmonic acid in the semi-dwarf mutant. A non-targeted metabolomics analysis by UHPLC-QTOF-MS/MS revealed a differential metabolic profile, with 16 and 9 metabolites showing higher intensities in the mutant and wild-type plants respectively. Among these metabolites, azelaic acid was identified. Gibberellic acid, jasmonic acid, and azelaic acid are involved in pathogen resistance, showing that this semi-dwarf line has an enhanced basal pathogen resistance in absence of pathogens, and therefore is of interest in breeding programs to fight against lodging, but also probably to increase pathogen resistance.

Non-targeted metabolic profiling of BW312 Hordeum vulgare semi dwarf mutant using UHPLC coupled to QTOF high resolution mass spectrometry.

Vitamin D is a secosterol hormone critical for bone growth and calcium homeostasis, produced in vertebrate skin by photolytic conversion of the cholesterol biosynthetic intermediate provitamin D. Insufficient levels of vitamin D especially in the case of low solar UV-B irradiation is often compensated by an intake of a dietary source of vitamin D of animal origin. Small amounts of vitamin D were described in a few plant species and considered as a peculiar feature of their phytochemical diversity. In this report we show the presence of vitamin D in the model plant Arabidopsis thaliana. This plant secosterol is a UV-B mediated derivative of provitamin D, the precursor of sitosterol. The present work will allow a further survey of vitamin D distribution in plant species.

Vitamin D in Arabidopsis thaliana.

Micropollutants and emerging organic contaminants (EOCs) have been widely studied in terms of persistance, removal, human risk assessment, toxicology, etc. Mass spectrometry imaging (MSI) offers the possibility of following the fate of a single pesticide in a plant leaf or a drug in the whole body of an animal, organ by organ. However, the admissibility of chronic low doses of complex mixtures for the ecosystem has not been assessed. How do micropollutants diffuse in the environment? How do living organisms cope with chronic exposure to a low dose of diverse micropollutants? Is there a cocktail effect or a chance for hormesis? Combining mass spectrometry imaging (MSI) and targeted and nontargeted liquid chromatography coupled to mass spectrometry (LC-MS), we attempt to answer these questions. We investigate the diversity of micropollutants at the exit of a water treatment facility, their diffusion in sludge and black poplar (Populus nigra), and their impact on a living organism. We reveal a specific tissue localization of micropollutants in peripheral leaf tissues, and an associated stress response from the plant, with stress hormones and tissue degradation markers induced in the plant growing near the water efflux.

In situ localization of micropollutants and associated stress response in Populus nigra leaves.

Micropollutants are increasingly monitored as their presence in the environment is rising due to human activities, and they are potential threats to living organisms.

Article	Year
Plant Sterol Diversity in Pollen from Angiosperms. Lipids\| PubMed ID: 25820807	2015
Non-targeted metabolic profiling of BW312 Hordeum vulgare semi dwarf mutant using UHPLC coupled to QTOF high resolution mass spectrometry. Scientific reports\| PubMed ID: 30181601	2018
Vitamin D in Arabidopsis thaliana. Scientific reports\| PubMed ID: 30397227	2018
In situ localization of micropollutants and associated stress response in Populus nigra leaves. Environment international\| PubMed ID: 30851483	2019
Xenobiotics metabolization in Salix alba leaves uncovered by mass spectrometry imaging. Metabolomics : Official journal of the Metabolomic Society\| PubMed ID: 31471668	2019

Claire Villette

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