Abstract
Salinity‐induced metabolic, ionic, and transcript modifications in plants have routinely been studied using whole plant tissues, which do not provide information on spatial tissue responses. The aim of this study was to assess the changes in the lipid profiles in a spatial manner and to quantify the changes in the elemental composition in roots of seedlings of four barley cultivars before and after a short‐term salt stress. We used a combination of liquid chromatography–tandem mass spectrometry, inductively coupled plasma mass spectrometry, matrix‐assisted laser desorption/ionization mass spectrometry imaging, and reverse transcription – quantitative real time polymerase chain reaction platforms to examine the molecular signatures of lipids, ions, and transcripts in three anatomically different seminal root tissues before and after salt stress. We found significant changes to the levels of major lipid classes including a decrease in the levels of lysoglycerophospholipids, ceramides, and hexosylceramides and an increase in the levels of glycerophospholipids, hydroxylated ceramides, and hexosylceramides. Our results revealed that modifications to lipid and transcript profiles in plant roots in response to a short‐term salt stress may involve recycling of major lipid species, such as phosphatidylcholine, via resynthesis from glycerophosphocholine.
Highlights
Chen et al, 2007; Dai et al, 2012)
Understanding the physiological and metabolic mechanisms that confer salt tolerance of barley is of Barley (Hordeum vulgare) is the most ecologically diverse grain world- agronomic and economic interest
In our previous work (Sarabia et al, 2018a), we developed a matrix-assisted laser desorption/ionization mass spectrometry imaging (MSI) (MALDI-MSI) method to analyse the spatial distribution of lipids and metabolites in longitudinal sections of roots of the barley cultivar Hindmarsh and applied this to investigate spatially resolved molecular changes in response to a short-term salt stress
Summary
Chen et al, 2007; Dai et al, 2012). Understanding the physiological and metabolic mechanisms that confer salt tolerance of barley is of Barley (Hordeum vulgare) is the most ecologically diverse grain world- agronomic and economic interest. Resolved metabolomics (Shelden, Dias, Jayasinghe, Bacic, & Roessner, 2016) and transcriptomics (Hill et al, 2016) were recently applied to analyse the molecular effects of a short-term salt stress in seminal roots of barley seedlings In both studies, root tissue was dissected into different developmentally distinct zones: root cap and zone of cell division (S1), zone of cell elongation (S2), and zone of cell maturation (S3), revealing spatial metabolite or gene expression gradients along the different developmental zones of the barley root. To investigate the spatially localized molecular signatures of salinity stress, we analysed changes in the composition, distribution, and saturation levels of several lipid species in dissected root tissues in response to a short-term high salt (150 mM of NaCl) stress using liquid chromatography–mass spectrometry (LC-MS) as well as MALDI-MSI-based lipidomics. Our study contributes new insights on salinity stress responses along different developmental barley root zones and suggests sites of lipid regulation that can be attributed to short-term salinity stress
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